Blend 2 cups half and half, chipotle pepper(s), bouillon cubes and garlic in a blender or food processor until well blended. Pour into a large saucepan; add onion powder, black pepper, remaining 2 cups of half and half and corn starch. Stirring constantly, bring to a boil; boil and stir for 1 minute or until very thick. Remove from heat.
Gradually stir in cheeses until melted. Add cooked pasta and stir until blended. Pour mixture into a greased 3-quart casserole dish (or 13 x 9-inch pan) and sprinkle with desired topping.
Bake for 25 to 30 minutes or until browned and bubbly around edges.
