Preheat oven to 400°F (200°C). Toss sliced potatoes with olive oil, 1/2 tsp salt, and 1/4 tsp pepper. Arrange in a single layer on a baking sheet and bake for 15-20 minutes until slightly tender.

In a large skillet over medium-high heat, brown the ground beef. Drain excess grease. Add the onion and cook for 4-5 minutes until softened. Stir in the garlic and cook for 1 minute more. Stir in Worcestershire sauce, the remaining 1/2 tsp salt, and 1/4 tsp pepper.

In a saucepan, melt butter over medium heat. Whisk in flour and cook for 1 minute. Gradually whisk in milk until smooth. Cook, stirring, for 5-7 minutes until thickened. Remove from heat and stir in 1 ½ cups of shredded cheese until melted.

Reduce oven temperature to 375°F (190°C). In a greased 9x13 inch baking dish, layer half the potatoes, all of the beef mixture, and half of the cheese sauce. Top with the remaining potatoes and the rest of the cheese sauce.

Sprinkle the remaining ½ cup of cheese on top. Bake for 25-30 minutes, until bubbly and golden brown. Let rest for 10 minutes before serving.