Preheat the oven to 170°C (338°F).
Sift whole wheat flour and baking powder together.
Whip eggs and oligosaccharide until foamy.
Add milk and vanilla extract and mix well.
Add the sifted flour mixture and gently fold with a spatula.
Line the pan with parchment paper and pour in the batter.
Bake in the preheated oven for 30–35 minutes.
Let it cool, then cut into serving pieces.