01 -
Arrange a rack approximately 15 cm below the broiler and preheat oven to 175°C (350°F). Dice the small yellow onion while the oven heats.
02 -
Split English muffins and place cut-side up on a rimmed baking sheet. Toast in oven until lightly browned, about 5 minutes, then remove and set oven to broil.
03 -
Heat olive oil in a large skillet over medium-high heat until shimmering. Add diced onion and cook, stirring occasionally, until softened, about 5 minutes. Add lean ground beef, Italian seasoning, garlic powder, kosher salt, and black pepper. Break meat into smaller pieces and cook until browned and cooked through, 5 to 7 minutes.
04 -
Stir pizza or marinara sauce into the beef mixture and cook until slightly thickened, about 3 minutes.
05 -
Distribute meat mixture evenly over toasted English muffin halves. Top each with shredded mozzarella cheese. Broil until cheese melts and bubbles, approximately 1 to 2 minutes.