Preheat oven to 375 degrees F. Line a baking sheet with parchment paper or aluminum foil and it set aside.
In a large skillet, melt the butter over medium heat. Cook the red bell pepper and garlic in the butter for 3 minutes. Add the spinach to the pan and cook, stirring, until just wilted.
Add the cream cheese and sour cream to the pan and cook until melted, stirring frequently. Add the Parmesan cheese, crushed red pepper flakes, and salt, and continue cooking until the cheese is melted. Remove from heat and set aside.
Unroll the crescent roll dough into a large rectangle on the parchment paper. Press seams together to seal them. Using a sharp knife or pizza cutter, cut the dough into a large triangle tree shape. Take the two outside triangles you cut off and press dough together down the center to form a second matching triangle. Spread the spinach dip evenly over one of the triangles. Top with the second triangle of crescent dough.
Cut 1-inch strips into the tree from the sides towards the center, leaving a strip of dough in the center uncut. Carefully twist each strip several times.
Bake for 13-15 minutes, or until the dough is golden. Serve warm.