Step 1: Prepare the Cake

1. Preheat your oven to 350°F (175°C). Grease and line two 9-inch round cake pans with parchment paper.
2. In a large bowl, sift together the flour, baking powder, baking soda, and salt. Set aside.
3. In another large bowl, beat the softened butter, granulated sugar, and brown sugar until light and fluffy (about 2-3 minutes).
4. Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.
5. Gradually add the dry ingredients to the wet mixture, alternating with milk and sour cream. Begin and end with the dry ingredients.
6. Fold in the crushed Oreo cookies until evenly distributed.
7. Divide the batter evenly between the prepared pans and smooth the tops with a spatula.
8. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean.
9. Cool the cakes in the pans for 10 minutes, then transfer them to a wire rack to cool completely.

Step 2: Make the Frosting

1. In a large bowl, beat the softened butter until creamy.
2. Gradually add the powdered sugar, one cup at a time, beating well after each addition.
3. Add the heavy cream and vanilla extract, and beat until smooth and fluffy.
4. Stir in the finely crushed Oreo cookies until fully incorporated.

Step 3: Assemble the Cake

1. Place one cake layer on a serving plate or cake stand. Spread a layer of frosting evenly on top.
2. Place the second cake layer on top and frost the entire cake, including the sides.
3. Decorate with whole Oreo cookies around the edges and sprinkle crushed Oreos on top for extra flair.

Step 4: Chill and Serve

1. Refrigerate the cake for at least 30 minutes to allow the frosting to set.
2. Slice and enjoy your homemade Cookies and Cream Cake!