Soak the raisins in milk. Combine the flours with salt and bicarbonate in a large bowl, mix them with a whisk.
Pour the raisins and milk into a blender and blend to dissolve raisins as much as possible. Combine the liquid obtained with the flours and knead with your hands until you get a smooth dough. Turn the oven to 360°F and let rest the cookie dough for 10 minutes.
Roll out the dough about 1/6 inch thick between two sheets of parchment paper. Cut the cookies and place them on a baking tray covered with parchment paper or a baking mat.
Bake the cookies for 12 minutes, take them out from the oven and allow them to cool before storing or serving.