Preheat your oven to 375F. Spray a 9-inch pie plate with nonstick cooking spray and set it aside. Getting this done first means you are not scrambling once the cream cheese mixture is ready.

In a medium mixing bowl, beat the softened cream cheese, sour cream, garlic powder, Italian seasoning, and red pepper flakes with a hand mixer until completely smooth. You should not see any lumps. If you do, your cream cheese was not warm enough; give it another minute on medium speed. This base is what gives the dip its structure, so take the time to get it smooth.

Spread the cream cheese mixture evenly across the bottom of the prepared pie plate. Use the back of a spoon or a small offset spatula to press it all the way to the edges. Even thickness means even heating.

Spoon the marinara over the cream cheese layer and spread it gently with the back of a spoon. Do not press hard or you will drag the layers together. You want the sauce sitting on top, not mixed in.

Sprinkle the parmesan evenly over the marinara, then top with the shredded mozzarella. The mozzarella goes on last so it gets that golden, bubbly top.

Arrange the 15 pepperoni slices across the top of the cheese. They will crisp slightly at the edges as they bake and release flavor into the cheese layer underneath.

Bake at 375F for 25-30 minutes. You are looking for bubbling around the edges, melted and lightly golden cheese on top, and pepperoni that has crisped at the edges. If the cheese is not browning by 25 minutes, give it another 5.

Serve immediately with crusty bread, pita chips, pretzel crisps, or tortilla chips. The dip will stay warm in the dish for a bit, but it is at its best right out of the oven.