Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper.
In a small skillet, heat olive oil over medium heat. Add sliced mushrooms and sauté for 5–6 minutes until browned and tender. Season mushrooms with a pinch of salt and pepper at the end of cooking. Set aside.
Lay the English muffin halves cut-side up on the prepared baking sheet.
Spoon about 2 tablespoons of marinara sauce on each muffin half. Spread evenly to the edges.
Sprinkle shredded vegan mozzarella generously over the sauce. Add sautéed mushrooms and diced bell peppers evenly across each piece. Sprinkle Italian seasoning over the top.
Bake for 10–12 minutes or until the cheese is melted and bubbly, and the edges of the muffins are golden. Broil briefly at the end for extra browning, if desired.
Remove from the oven and top with fresh basil leaves. Serve warm.
Notes
Refrigerator: Leftover English muffin pizzas can be stored in an airtight container in the refrigerator for up to 3 days.
Freezer: Wrap each individual pizza in plastic wrap and then place them in a freezer-safe bag or container. They can be kept in the freezer for up to 2 months.
To reheat: Place the English muffin pizzas on a baking sheet and heat in the oven at 350°F for about 10 minutes, or until heated through.