Preheat the oven to 425 degrees F (220 degrees C).
In a medium bowl, stir together the flour, baking powder, sugar, salt and cream of tartar. Cut in butter using a pastry cutter or a fork until it is the size of peas. Make a well in the center of the mixture and measure the milk, cheese and thyme into the bowl. Gently mix until a soft dough forms.
Roll or pat out on a floured surface to 3/4 inch thick. Cut into circles and place on a baking sheet.
Bake for 10 minutes in the preheated oven, or until the bottoms of the biscuits are golden brown.