Using a stand mixer or hand mixer, beat the butter, eggs, sugar, and vanilla together. Next, add the flour and baking powder until well-combined.
Preheat oven to 350°F. Line a baking sheet with parchment paper. Next, form small, round balls out of the dough (about the size of a walnut).
Arrange the dough balls on the baking sheet about an inch apart. Bake for about 15-20 minutes (you'll want to pull them out of the oven while they're still white, not golden brown).
Using a knife, cut out a small hole in the center of each cookie.
To make the filling, combine the dulce de leche with the cookie crumbs and crushed walnuts.
Fill in each hole with the dulce de leche filling. Press two cookies together to form a peach shape.
Fill two medium-sized bowls with a cup of milk. Dye one bowl of milk pink using pink food coloring. In the other bowl, combine pink food coloring and green food coloring to create a peach color.
Dip one side of the cookie into the pink milk and the other side into the peach milk. Dunk the cookie into a bowl full of sugar and place it on a baking sheet lined with parchment paper. Repeat until you have no more cookies left. Allow the cookies to set at room temperature overnight.
Decorate the cookies with small leaves. Serve and enjoy!