Mix the flour, baking powder and sugar in a bowl. Add the oil. Dissolve the yeast in warm water and add. Knead everything into a tough dough with the hand mixer.
Line a baking sheet with parchment paper. Use a trowel to put small blobs of the dough on the tray. The amount is enough for approx. 15 snails.
For the crumble, put the flour with sugar and room temperature butter in a bowl and knead until the mixture is crumbly. Spread the crumble on the snails. Bake at 170 degrees for about 20 minutes.