Preheat oven to 450 degrees. Line a rimmed baking sheet with aluminum foil.: When you open the oven to set it to 450 degrees , notice the dry heat that will encourage crisping on the bread surfaces. The foil on a rimmed baking sheet helps with cleanup and reflects heat for even browning, and the faint metallic scent as it warms is normal. This temperature is high enough to quickly toast the bread without drying the interior. A common mistake is to skip the foil and then struggle with stubborn baked on butter, which makes cleanup harder and can burn residues onto the pan.
In a bowl, stir together all sauce ingredients.: The moment you combine the canned crushed tomatoes , extra-virgin olive oil , dried Italian seasoning , sugar , salt , black pepper , and crushed red pepper flakes , inhale the herbal and tomato aromas that bloom as they mingle. Stirring releases the olive oil into the tomato, smoothing the texture and distributing the herbs evenly. This step sets the flavor backbone for the whole pizza, so taste and adjust lightly. Avoid overmixing to the point of creating a watery sauce, which can make the bread soggy when spread.
Cut bread in half crosswise and then cut each piece horizontally. Brush crust sides with oil.: As you cut the French bread , observe its crumb structure; a slightly firm loaf will hold up best. Brushing the exterior crusts with extra-virgin olive oil promotes a golden, glossy finish and prevents the outer crust from drying out. The oil also carries flavor and helps the buttered surface on the interior develop an attractive color. One thing to watch for is applying too much oil, it can pool and make the crust greasy rather than crisp.
Place bread pieces crust side down on prepared baking sheet.: Laying the halves crust side down centers the cut surfaces up to receive butter, sauce, and cheese. You should hear a slight thud as the bread hits the sheet, and as it bakes the heat will move through the crumb, firming the base while allowing the top to bubble. Make sure pieces are arranged without overlapping to ensure even heat circulation. Overcrowding will produce uneven toasting and limp centers.
In a small bowl, stir together melted butter, garlic powder, and salt. Brush mixture on the cut sides of the bread.: The moment you whisk the melted butter with garlic powder and salt , the aroma of garlic will become pronounced, signaling flavor depth for the toast layer. Brushing this mixture provides a rich, savory barrier that crisps under heat, and it helps the sauce adhere to the surface. Apply an even coat and allow excess to drip back into the bowl rather than pooling on the bread. If you apply too much, the butter can make the bread soggy or cause flare ups in the oven.
Place in oven for 5 minutes, or until browned around the edges.: During this brief toasting step you will see the buttered cut surface take on a warm golden color and smell the nutty butter aroma. The 5 minute window is designed to create a toasted foundation that resists sogginess once sauce is added. Look for small browned spots at the edges as your cue to remove the bread. A common error is leaving it in too long, which dries the interior and reduces the pleasant chewiness you want.
Spread sauce on bread pieces. Top with mozzarella cheese, Parmesan cheese, and pepperoni slices.: After toasting, spreading the sauce releases a burst of tomato fragrance and creates a glossy bed for the cheeses. Sprinkle mozzarella cheese evenly so it melts uniformly, dust with Parmesan cheese for savory complexity, and place pepperoni slices with some spacing to allow edges to crisp. The visual cue is a shiny red sauce dotted by white cheese and circular pepperoni. Avoid piling toppings too thickly, which will lengthen bake time and can prevent proper browning.
Bake for another 12 to 15 minutes.: As the pizza returns to the oven, listen for the gentle bubble of melting mozzarella and watch the pepperoni edges begin to curl and crisp. The cheese should be uniformly melted with golden flecks and the crust edges deeper brown, while the sauce simmers slightly under the cheese. This bake time gives the right balance of melted interior and crisp exterior. If you underbake it, the cheese will be pale and not fully cohesive, and if you overbake it, the bread can become too dry and the pepperoni overly crisped.