Dice tomatoes, melt butter. Preheat the oven to 180 ° C (convection 160 ° C). Grease the tray, mix the flour, baking powder, salt and semolina. Whisk eggs, milk and pesto together. With butter; Mix the flour mixture and tomatoes.
Pour the batter into the recesses of the muffin tray. Bake in the oven for 35 minutes (center).
Cut the tomatoes and mozzarella into slices. Spread over the muffins after 20 minutes. Serve garnished with basil.