In medium saucepan, heat oil over medium heat until shimmering. Add pancetta, cook until crisp, stirring occasionally, about 4 minutes. Leaving rendered fat in pan, transfer pancetta to paper towel-lined plate. Set aside.
Add onions to pan and cook, stirring frequently until soft, about 2 minutes. Stir in garlic, cook until fragrant, about 30 seconds. Add butter, stir until melted. Add flour and cook 1 minute, stirring constantly. Whisk in wine and milk until smooth. Bring to boil and reduce to simmer. Cook, stirring occasionally, 2 minutes.
Remove from heat and stir in cheddar, gouda and parmesan until melted and smooth. Stir in cream. Add salt and pepper to taste. Transfer cooked macaroni to large bowl. Stir in cheese sauce. Garnish with reserved pancetta bits, and if desired, fresh thyme.