Notes: Reserve some cheese and cooked bacon for the last 10 minutes of cook time so you are rewarded with a cheesy, crispy topping!
- Place a large frying pan over medium-heat. Add bacon and cook until crispy, about 8-10 minutes.
- Heat a medium-sized pot over medium heat. Add in butter, waiting until it melts and is bubbling before adding flour. Whisk very frequently for about 5 minutes, or until the roux has deepened in colour. Add garlic in the last minute and cook until aromatic.
- In a separate bowl, mix together the milk, cream, salt, pepper, cayenne, oregano, and mustard. Pour into roux, whisking constantly. Bring to a boil and add 2 cups of cheese. Stir until melted and blended. Remove from heat.
- Preheat oven to 350°F. Grease a 9x13 inch baking dish. Place in enough potatoes to cover the bottom. Add some sauce and sprinkle with bacon. Repeat again until no potatoes or sauce remains (I save a bit extra sauce to pour over the top potatoes for extra coverage and creaminess.) Reserve some bacon and cheese for topping.
- Bake for 1 hour 10 minutes, uncovered until potatoes are soft. In the last 10 minutes, top with bacon and cheese!