Heat olive oil in a large skillet over medium heat. Add garlic; cook and stir until fragrant, about 30 seconds. Sprinkle in flour and black pepper; cook, whisking constantly, for 1 minute. Pour in milk; whisk constantly until sauce thickens, about 3 minutes. Remove from heat; stir in Parmesan cheese.
Lay pizza crust on a piece of parchment paper. Spread sauce over crust. Add spinach in an even layer. Sprinkle mozzarella cheese evenly on top. Cover with chicken, artichoke hearts, feta cheese, and bacon. Sprinkle red pepper flakes on top.
Bake in the preheated oven until cheese is melted and golden, about 12 minutes.