1. Preheat the oven to 350F.
2. In a mixer, beat the butter and sugar together for 4 minutes. Add the eggs and vanilla extract; mix.
3. Add the flour mixed beforehand with the yeast, bicarbonate, and salt.
4. Add the milk, whipping slowly. Reserve half of the cake batter for the chocolate biscuits. Simply add the cocoa powder to this batter.
5. Transfer the vanilla preparation into a pastry bag with a simple nozzle. On a baking sheet covered with parchment paper, shape small mounds of batter, spaced apart.
6. For the chocolate biscuits, as for the vanilla biscuits, shape on a baking sheet.
7. Bake for 10 minutes. Remove from the oven and cool on a rack.
8. For the cream: mix the butter with the icing sugar, coffee extract, and water.
9. Fill the vanilla whoopies with coffee cream and top with cocoa whoopies.
10. For the glaze: mix the icing sugar, coffee food coloring, and water. Glaze and serve.