High Protein Millionaire’s Shortbread (Easy No-Bake)
A no-bake high protein take on classic millionaire’s shortbread, with a pressed oat base, smooth cashew caramel, and a firm dark chocolate topping.
One of my favourtie treats as a kid was Millionaire’s Shortbread from the local WI (Women’s Institute) market. A buttery base, sweet sticky caramel and a chunky layer on top. What could be better? This high protein millionaire’s shortbread keeps everything that makes the classic work, but contains far less sugar and saturated fat, and gives you four times more protein than the original.
It’s an indulgent treat that helps boost your protein intake for the day, without losing the pleasure of a proper sweet snack to have for elevenses (yes it’s a real thing and not just for Hobbits) or with your afternoon cuppa. It’s not diet food — but if you’re trying to bulk up or gain, this is exactly the kind of thing that you need.
Technically, it isn’t traditional millionaire’s shortbread — it’s no-bake and skips a cooked caramel — but the combination of ingredients manages to create something that genuinely tastes and feels like the original.
Ingredients Breakdown
Oat flour
Forms a smooth, sturdy base that presses cleanly and gives a shortbread-style texture without baking.
I never buy oat flour – for some reason it is extremely expensive here. You can make your own by grinding some oats in a coffee grinder.
Protein powder
Raises the protein content while helping both the base and caramel set firmly; neutral or vanilla powders work best to fit with the flavour profile.
You can use whichever style you like – whey, egg, pea, etc. Just pay attention to the moisture content if using a vegan protein powder. They tend to be a little drier and you might want to add a splash more liquid – especially to the caramel layer.
Important note, this will be used in both the base and the caramel layer so make sure not to put it all in at once!
Cashew butter
Creates a thick, creamy caramel layer with a mild flavour and good structure once chilled. Peanut butter can be used here too and will slightly boost the protein numbers, but it will alter the taste significantly. You’ll end up with a Snickers Millionaire’s Shortbread, which also sounds great to be fair.
Maple syrup
Adds sweetness and moisture while keeping the caramel smooth and spreadable. Any liquid sweetener would work here, but granulated sugar would not as it would thicken the caramel too much.
Coconut oil
Binds the base and helps the chocolate topping set with a clean snap; it firms up reliably at fridge temperature.
Dark chocolate
Forms a firm top layer that balances the sweetness underneath; higher cocoa percentages keep the slice from becoming overly sweet.
Milk
Loosens the caramel just enough to spread evenly; add gradually to control consistency and ensure a clean set. Plant based milk works just as well here.
Salt
Balances sweetness and sharpens flavour across all layers; a small amount makes a noticeable difference.
How to Make High Protein Millionaire’s Shortbread
Prepare the tin
Line a 23 × 23 cm square tin, or a similar-sized traybake tin, with baking paper, leaving enough overhang to lift the slice out cleanly. Press the paper firmly into the corners so the layers sit evenly.
Make the shortbread base
In a large bowl, mix the oat flour, 100 g of protein powder, and salt until evenly combined. Add the melted coconut oil and maple syrup, then stir until a soft, uniform dough forms with no dry patches.
Press and chill the base
Transfer the mixture to the lined tin and spread it out roughly. Use the flat base of a glass to press it down firmly and evenly, working right into the corners. The surface should feel compact and level, not crumbly. Refrigerate for 20–30 minutes, until firm to the touch.
Mix the caramel layer
In a bowl, stir together the cashew butter, maple syrup, and vanilla until smooth. Add 150g of protein powder and salt, mixing until thick and glossy. Gradually add milk, one tablespoon at a time, until the caramel is spreadable but still holds its shape.
Tip: If the cashew butter is very thick, warm it gently until just fluid, using a bowl over warm water or 10–15 seconds in the microwave. It should be soft and pourable, not hot.
Spread and set the caramel
Spoon the caramel over the chilled base and spread it evenly with a spatula. Tap the tin lightly on the counter to level the surface. Refrigerate for about 30 minutes, until set and no longer sticky.
Melt the chocolate topping
Melt the dark chocolate and coconut oil gently over low heat or in short microwave bursts, stirring until smooth. Avoid overheating, as this can affect how the chocolate sets.
Finish the slice
Pour the melted chocolate over the caramel layer and tilt the tin to coat evenly. If you want to make it a bit posher, sparingly sprinkle flaky salt over the top before chilling.
Chill and set
Return the tin to the fridge for 45–60 minutes, until the chocolate is fully set and firm with a clean snap.
Slice cleanly
Lift the slice out using the baking paper. For neat edges, use a sharp knife warmed under hot water and wiped dry between cuts. Slice into around 20 squares.
Storage & Shelf Life
Store the sliced high protein millionaire’s shortbread in an airtight container in the fridge, where it will keep well for 5–6 days without drying out. The layers firm up nicely once chilled, making it easy to stack and transport. For longer storage, freeze individual pieces and thaw in the fridge
Make It Vegan
This recipe is already vegan if you use a plant-based protein powder and dairy-free dark chocolate. Check that your chocolate contains no milk solids and that your protein powder isn’t whey or egg based. Everything else — the oat base, cashew caramel, and setting method — works the same without adjustment.
Vegan protein powders absorb more liquid, so if the caramel feels stiff or dry, add a little extra milk until it spreads smoothly. If your vegan chocolate sets slightly softer, chill the slice a little longer before cutting for cleaner edges.
High Protein Millionaire’s Shortbread
Ingredients
Base
- 300 g oat flour very finely ground
- 100 g vanilla or neutral protein powder
- 100 g coconut oil melted
- 100 g maple syrup
- Pinch of salt
Protein Caramel
- 250 g smooth cashew butter
- 150 g vanilla protein powder
- 100 g maple syrup
- 2 tsp vanilla extract
- 8 tbsp milk dairy or plant
- Generous pinch of salt
Chocolate Top
- 200 g dark chocolate 70%+
- 1.5 tsp oconut oil
- Flaky salt optional
Instructions
- Line a 23 × 23 cm square tin (or similar-sized traybake tin) with baking paper, leaving overhang for lifting.
- Mix the oat flour, protein powder, and salt in a bowl. Stir in the melted coconut oil and maple syrup until a uniform dough forms.
- Press the base firmly into the tin, using the flat base of a glass to compact it evenly. Chill for 20–30 minutes until firm.
- Stir the cashew butter, maple syrup, and vanilla until smooth. Add the protein powder and salt, mixing until thick and glossy.
- Add warm milk gradually until the caramel is spreadable but holds its shape. Spread evenly over the base and chill for about 30 minutes.
- Melt the dark chocolate with the coconut oil gently, stirring until smooth.
- Pour over the caramel layer and tilt the tin to coat evenly. Sprinkle with flaky salt if using.
- Chill for 45–60 minutes until fully set. Lift out and slice into 20 squares.
Notes
- Chocolate intensity: Use 75–85% dark chocolate for a firmer, less sweet topping.
- Salted caramel: Increase the salt slightly in the caramel and finish with flaky salt.
- Mocha: Add ½ tsp espresso powder to the caramel for a subtle coffee note.
- Oat flour can be made by finely blending rolled oats.
- Cashew butter can be replaced with almond butter (milder) or peanut butter (stronger flavour).
Keep refrigerated in an airtight container for 5–6 days. Freeze sliced pieces for up to 2 months and thaw in the fridge.
Make It Vegan
Use a plant-based protein powder and dairy-free dark chocolate. Vegan protein powders absorb more liquid, so add a little extra milk to the caramel if it feels stiff. Chill slightly longer if the chocolate sets softer.Cashew butter brands vary a lot in thickness. Warm the cashew butter gently before mixing, or add plant milk a tablespoon at a time until the caramel spreads smoothly without turning runny.
Make sure each layer is fully set before adding the next. Chilling the slice for at least 45 minutes after the chocolate goes on, and wiping the knife clean between cuts, makes a big difference.
Yes. Once sliced, it keeps well in the fridge for up to 5–6 days in an airtight container, and the texture actually improves after the first day.
It freezes well. Slice it first, freeze in a single layer, then transfer to a container; thaw in the fridge so the caramel and chocolate set cleanly again.
Serve it straight from the fridge for the cleanest layers, or let it sit at room temperature for 10 minutes if you prefer a slightly softer caramel.
