Start by washing the potatoes, and slicing them into 1/4 inch thick slices.
Place them in an electric pressure cooker, with vegetable stock. Cover with the lid, seal and cook on high pressure for 1 minute. If you don't have a pressure cooker, just boil the potatoes over the stovetop until they're soft but not too soft that they start breaking.
Once the potatoes are cooked, take them out and set aside. In the pressure cooker, on saute mode, melt the butter. Then add the garlic and cook for 1 minute until fragrant, add thyme, cream, and cheddar cheese. Stir until the sauce is smooth.
Arrange the cooked potato slices in a casserole dish, pour the cheese sauce over the potatoes and top with more grated cheddar cheese.
Broil in the oven for 5 minutes or until the top is bubbly and slightly browned.