Basic Pate Brisse (Shortcrust Pastry)
Press dough inside fluted mini tart pans (~4.5 inch diameter) with removable bottoms. Roll rolling pin over tops of tarts to cut off any dough above the edges. Prick dough with a fork in several places. Allow to rest in the refrigerator for 15-20 minutes. Place parchment paper inside tart pans, covering sides and fill with pie weights. Blind bake for 25 minutes until dough is a golden brown. Remove from oven and set aside.
While tart shells are blind baking, slice leeks into thin rounds and sauté over medium/medium low heat with a splash of olive oil, small pat of butter and sprinkle of salt and pepper until they are soft and translucent. Mix ~1 tablespoon chopped thyme leaves, and a sprinkle of pepper into goat cheese. Stir to soften the cheese.
When beets are cool enough to handle, remove skins and slice very thinly and evenly, ideally using a mandolin.
When tart shells come out of oven, fill bottoms with sautéed leeks and then dot goat cheese evenly on top, using your finger or a fork to gently distribute the cheese.
Bake tarts for ~10 minutes until cheese has softened. Remove from oven and neatly place beet slices on the top, drizzle with a little olive oil, sprinkle with remaining teaspoon chopped thyme leaves and heat in oven until warm, ~5-7 minutes, taking care to ensure beets do not dry out.
Remove from pie pans, garnish with a spring of thyme and serve with a green salad.