High-Protein Birthday Cake in a Jar (Refined-Sugar-Free)

Yes, mama — you can have cake and lose the baby weight. 🎂

This Birthday Cake in a Jar is one of my favorite proof-it's-possible treats: high in protein, refined-sugar-free, made with a flax egg, and layered in a little jar like the cutest funfetti parfait. It is not a five-minute recipe — it's the kind of thing you make on a slow Sunday — but it is absolutely worth it once in a while.

Because here's the truth: the diets that make you swear off dessert forever are the diets you quit. A plan you can actually stick to has room for treats — you just make them work for you.

Mama tip: Treats aren't "cheating." A high-protein, single-serve dessert you planned for is part of the plan, not a break from it.

Why this cake fits your plan

• High in protein — protein powder in both the cake and the frosting
• Refined-sugar-free — sweetened with monk fruit
• No eggs — a simple flax egg does the job
• Single-serve — it makes one small jar, so there's no "oops, I ate the whole pan"
• Approximately ~350 calories and ~20g protein per jar (this varies a little depending on the exact brands you use)

Ingredients

Cake

• ½ tbsp ground flaxseed + 1½ tbsp water (flax egg)
• 1 oz Siggi's coconut yogurt
• 4 tbsp unsweetened applesauce
• 2 tbsp monk fruit sweetener
• ¼ tsp lemon juice or apple cider vinegar
• 3 tbsp oat flour (Bob's Red Mill)
• 1 tbsp birthday cake or vanilla protein powder (Orgain)
• 1 tsp birthday cake extract
• scant ¼ tsp baking soda
• pinch of salt

Frosting

• 2 oz Siggi's coconut yogurt
• 1 tbsp birthday cake or vanilla protein powder (Orgain)

Topping

• 3 tsp rainbow sprinkles (Supernatural Softies)

How to make it

Oven: 350°F · Bake: 30–40 minutes

1. Whisk the flaxseed + water and let it sit 5 minutes until gloopy.
2. Preheat the oven to 350°F and grease a small loaf pan.
3. Whisk together the yogurt, applesauce, monk fruit, lemon juice, and flax egg until smooth.
4. Fold in the oat flour, protein powder, baking soda, and salt — don't overmix. Let the batter rest 5 minutes (oat flour needs it).
5. Pour into the pan and bake 30–40 minutes, until a toothpick comes out clean.
6. Cool completely before assembling (warm cake = melty frosting).
7. Stir the frosting yogurt + protein powder until smooth and thick.
8. Build your jar: flip a small glass jar upside down and press the rim into the cake to punch out circles — you want 4 layers. Drop one cake circle in, add frosting, then repeat: cake, frosting, cake, frosting.
9. Finish with a shower of sprinkles. 🌈

Fitting it into your day

Plan for it like any other meal: log the ~350 calories and ~20g protein, and let it be your sweet for the day. If you follow a calorie target, slot it in where your yogurt or fruit bowl might normally go — same idea, a lot more fun. Treats like this, once in a while, are exactly what keep you consistent for the long haul.

Want a whole plan with room built in for treats like this — plus the calorie calculator, weekly check-ins, and the full recipe vault? My Skinny Mamas membership is coming soon — hop on the early list and you'll be first in. 💕