• Preheat oven to 350°F (175°C). Line two 8-inch round cake pans with parchment paper and lightly grease the sides.
• In a medium bowl, whisk together the flour, baking powder, and salt until evenly combined. Set aside.
• Brown the butter by melting it in a small saucepan over medium heat. Stir constantly as it foams and turns golden with brown specks forming at the bottom. Remove from heat and let cool for 10–15 minutes until warm, not hot.
• In a large bowl, whisk the browned butter and granulated sugar until smooth and glossy.
• Add the eggs one at a time, whisking well after each addition. Stir in the vanilla extract until fully incorporated.
• Add the dry ingredients to the wet ingredients and gently fold with a spatula until just combined. Do not overmix. The dough will be thick and soft.
• Fold in the M&Ms, reserving a small handful to press on top if desired.
• Divide the dough evenly between the prepared pans and press into smooth, even layers.
• Bake for 18–22 minutes, until the edges are lightly golden and the centers look just set. Avoid overbaking to keep the layers soft.
• Cool the cookie layers completely in the pans, then chill for 20–30 minutes before assembling for easier frosting.

Cream Cheese Frosting & Assembly

• In a medium bowl, beat the softened butter and cream cheese together until smooth and creamy.
• Gradually add the powdered sugar and salt, mixing until fluffy and fully combined.
• Add the vanilla extract and 1 tablespoon of milk. Beat until smooth, adding more milk as needed to reach a spreadable consistency.
• Divide the frosting evenly into two bowls. Leave one bowl white and tint the other with blue gel food coloring.
• Place one cookie cake layer on a serving plate. Spread an even layer of blue frosting over the top.
• Place the second cookie layer on top and gently press down.
• Frost the top with white frosting, smoothing or piping as desired. Decorate with sprinkles or additional M&Ms.