Preheat oven to 400ºF. Line 12 muffin cups with paper liners. In a large bowl, whisk together flour, sugar, baking powder, salt, basil and baking soda until combined. Stir in cheddar cubes.
In a medium bowl, whisk together sour cream, eggs and butter until smooth. Stir into flour mixture just until well combined and no dry spots remain; stir in sweet pepper (batter will be very thick). Spoon batter into muffin cups, dividing evenly. Spoon 1 tsp pizza sauce on top of each muffin; sprinkle each with shredded mozzarella.
Bake about 20 minutes, until golden and a toothpick inserted in centre of one of middle muffins comes out clean. Let muffins cool in pan at least 5 minutes before removing, then let cool completely on a wire rack.
You can freeze muffins in an airtight container for up to 1 month; defrost at room temperature.