Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a small bowl, combine 0.5 cup tomato paste and 0.25 cup water. Stir in 1 teaspoon garam masala, 0.5 teaspoon ground cumin, 0.25 teaspoon turmeric powder, 0.5 teaspoon grated fresh ginger, 1 clove minced garlic, 0.25 teaspoon salt, and a pinch of black pepper until smooth.
Cut 4 ounces paneer into 1/2-inch cubes.
Thinly slice 0.5 small red onion and 0.5 small green bell pepper.
Place 2 pieces of naan bread on the prepared baking sheet. Spread half of the spiced tomato sauce evenly over each piece of naan, leaving a small border around the edges.
Evenly sprinkle the cubed paneer, sliced red onion, and sliced green bell pepper over each naan.
Generously top each naan with 1 cup shredded mozzarella cheese.
Bake for 10–12 minutes, or until the cheese is melted and bubbly and the naan edges are golden brown and slightly crispy.
Remove from the oven and let cool for 1–2 minutes. Garnish with 2 tablespoons fresh chopped cilantro before slicing and serving.
Store any leftovers in an airtight container in the refrigerator for up to 3 days. Reheat in the oven or a toaster oven before serving.