Preheat the oven to 400 degrees F. Line a baking sheet with parchment paper.
Divide the dough into 23 pieces. Roll each piece into a small ball. To make a tree shape: Arrange a row of 6 balls of dough on the prepared baking sheet, then a row of 5 balls on top of that, a row of 4 balls on top of that, then 3, then 2 and then 1. Be sure to leave a little room between each of the dough balls--maybe 1/4 to 1/2 inch--as they will expand as they bake.
Cut each of the 2 remaining balls in half to create 4 pieces. Place those cut-side down at the base of the tree in 2 rows of 2 to create a trunk for the tree.
Using your hand or a rolling pin, flatten the dough until the rolls are just touching. Brush the tops of the dough with half of the olive oil and sprinkle with 1 1/2 teaspoons of the Italian seasoning. Bake for 10 minutes. While the tree is in the oven, mix the Alfredo and pesto in a small bowl and set aside.
Remove the baking sheet from the oven and brush the dough again with the other half of the olive oil. Use a spoon or a spatula to spread the sauce mixture over the tree, leaving a 1/2-inch gap around the edge. Sprinkle the mozzarella over top of the sauce. Decorate the tree by creating a garland with the bell pepper and ornaments with the tomatoes and pepperoni. Sprinkle the remaining 1/2 teaspoon Italian seasoning over on the tree trunk. Bake until the cheese is melted and the crust is golden, an additional 15 minutes.
Transfer to a serving board. Garnish with the Parmesan and fresh basil leaves.