Clabber Girl Pie Crust:
Mix the flour, Clabber Girl Baking Powder and salt in a large bowl. Add the butter. Using a pastry blender or your fingers, cut the butter into the flour until the mixture resembles coarse bread crumbs with some pea-size pieces of butter. Gradually stir in enough of the water for the dough to clump together. Gather up the dough and form into a disc, wrap in plastic wrap, and refrigerate until chilled but not hard, 1-2 hours. (You can make the crust in advance and store in the freezer for up to 3 days. No need to thaw the crust before baking.)
In a medium sized bowl, add eggs and whisk. Add milk, salt, pepper, thyme leaves and garlic; whisk to fully combine. Add cheese and mix together. Place in refrigerator until ready to use.
On a lightly floured work surface, roll out the dough into a 1/8-inch thick round. Transfer to a 10-inch pie dish, trimming the dough to a 1/2-inch overhang around the edges of the dish. Tuck the overhang under the dough on the rim and flute the edges. Prick holes in the bottom with a fork.
Preheat oven to 350 degrees F. Layer half the zucchini slices in the bottom of tart shell. Add egg mixture to the tart, being careful no to overfill the shell. Layer the remaining zucchini slices on the filling, pressing slices in slightly. Sprinkle with 1-1/2 tsp. fresh thyme leaves. Bake in preheated 350 degrees F. oven for 30-40 mins. or until golden brown and eggs are set.
Yield one 10-inch tart.