Add butter to bacon fat in skillet. Heat over medium-high heat until butter is melted. Add onion; cook 2 to 3 minutes, stirring frequently, until crisp-tender. Add flour, thyme and pepper; cook and stir until well blended. Gradually stir in half-and-half and bouillon granules. Heat to boiling, stirring constantly; boil and stir 1 minute. Remove from heat; stir in Parmesan cheese.