Step 1: Make the Cookies

1. Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
2. Prepare Dry Ingredients: In a bowl, whisk together the flour, baking powder, and salt. Set aside.
3. Cream Butter and Sugar: In a large bowl, beat the butter and sugar until light and fluffy. Add the egg and vanilla, and beat until smooth. Add milk and mix well.
4. Combine and Shape: Gradually add the dry ingredients to the wet mixture, mixing until combined. Scoop small balls (about a tablespoon) of dough onto the prepared baking sheet, flattening them slightly with your fingers.
5. Bake: Bake for 8-10 minutes or until edges are lightly golden. Let cool completely on a wire rack.

Step 2: Prepare the Filling

1. In a bowl, fold the whipped heavy cream into the vanilla pudding until smooth and fluffy. Chill until ready to use.

Step 3: Make the Ganache

1. In a microwave-safe bowl, heat the heavy cream until hot (about 30 seconds).
2. Add the chocolate chips and let sit for 1-2 minutes, then stir until smooth.

Step 4: Assemble the Cookies

1. Fill: Spoon a small amount of vanilla cream filling onto the flat side of half the cookies. Top with another cookie to create a sandwich.
2. Dip: Dip the top of each cookie sandwich into the chocolate ganache or drizzle over the top.
3. Chill and Serve: Refrigerate the cookies for 10-15 minutes to set the ganache.