Mix starter, water, olive oil, bread flour, and salt in a stand mixer on low for 5-7 minutes. Dough will look like thick batter — do not add more flour. Cover and rest 30 minutes.

Perform two rounds of stretch-and-folds with a 30-minute rest between each. This builds the gluten structure.

Add 3 tbsp olive oil to a 9x13 metal pan. Transfer dough and gently fold edges inward. Coax toward corners (it won't reach yet). Cover and let rise at room temperature 6-7 hours until bubbly and puffed.

Preheat oven to 450°F. Use wet fingers to gently press dough into corners. Sprinkle half the cheese blend all the way to the metal edges (this creates the frico crust). Add pepperoni and toppings, then remaining cheese. Ladle sauce in two racing stripes down the length.

Bake on the lowest oven rack for 25 minutes until cheese is deeply golden and edges are crispy. Immediately run a knife around the perimeter to loosen. Slide onto a cutting board and rest 5 minutes before slicing into 8 rectangles.