Heat oven to 350 degrees. Cut pepper into half-inch squares, and set aside. Heat the olive oil in a medium skillet over medium-high heat. Add the onions and garlic, and cook until translucent, about 7 minutes. Add sausage, breaking the meat into small pieces with a spoon. Cook until sausage is cooked through, about 8 minutes.
Slice the cream puffs crosswise. Spoon about 1 teaspoon of sausage filling into the bottom half, add a piece of red pepper, then replace the top half. Transfer the profiteroles to a baking sheet, place in the oven, and bake until warm, about 2 minutes. Garnish each with a parsley leaf, and serve immediately.
Pork sausage can be substituted for the chicken, turkey, or veal.