In a large mixing bowl sift together flour, baking powder, and salt.
150 g flour, 1 tsp baking powder, 1/2 tsp salt
In a separate bowl whisk the butter in a stand mixer until smooth and creamy, about 3 minutes.
150 g softened butter
Into to the butter add condensed milk, sugar, and sourdough starter. Mix well until everything is well incorporated, be sure to scrape down the walls of the bowl.
200 g condensed milk, 40 g powdered sugar, 50 g sourdough starter
Fold the sifted flour into the butter mixture with a spatula. Do not over mix the dough, it should be very soft.
Place the dough into the fridge for about 30 minutes or 1 hour, this will prevent the butter from melting too much.
Preheat your oven to 350 °F.
Remove the dough from the fridge and using an ice cream scoop, scoop the dough and form in into a ball. If you're adding sprinkles or m&ms, add them on here.
Place on a baking sheet and bake for about 10 minutes or until the bottom of the cookies is golden. These bake fairly quickly so be watchful.
Remove from the baking sheet to a cooling rack for about 15 minutes.
If you're adding a glaze, now is the time to do so. A simple glaze that we love is powdered sugar with lemon juice.
Enjoy!