Make the black pepper pie dough: in a large bowl, whisk together the flour, thyme, salt, and pepper. Add the butter and toss gently to coat the pieces with flour. Cut in the butter using a pastry blender or squeeze the pieces between your fingers until the biggest ones are the size of almonds and the smallest are about the size of peas. Add half of the water and work it in with a fork. Continue adding the water a tablespoon at a time as needed until the mixture forms a shaggy dough.

Gently knead the dough together in the bowl until it clumps together. Shape the dough into a disk and wrap it tightly in plastic wrap. Chill for 1 hour or up to 3 days.

Preheat the oven to 425F.

On a lightly floured surface, roll the chilled pie dough into 13-inch circle. Transfer to a 9-inch pie pan. Trim the excess dough to an inch from the edge of the pan, tuck the excess under, and crimp around the edge as desired. Poke the bottom of the crust all over with a fork and freeze for 15 minutes.

Set a piece of parchment paper inside the pie crust and fill the pan with pie weights or dried beans. Place the pie pan on a rimmed baking sheet and bake for 15 to 18 minutes, until the edges are starting to turn golden brown. Carefully remove the parchment and weights. Return the pan to the oven and bake for 3 to 5 more minutes, until the bottom of the crust looks matte and set. Set the crust aside to cool and reduce the oven temperature 350F.

Make the filling: in a large skillet over medium heat, heat the butter and olive oil. Add the garlic and cook, stirring often, until light golden brown, about 5 minutes. Remove the garlic from the skillet and set aside. Add the chard stems and 1/4 teaspoon of salt and cook, stirring occasionally, until the stems have softened slightly, about 3 minutes. Add the chard leaves, 1/4 teaspoon of the salt, and 1/4 teaspoon of the pepper and cook, stirring frequently, until the leaves are wilted.

2 to 3 minutes more. Remove the pan from the heat and stir in the caramelized garlic.

In a medium bowl, whisk together the eggs, cream, 1/2 cup of the cheese, and the remaining 1/4 teaspoon each of the salt and pepper. Add 3/4 cup of the chard mixture to the parbaked crust in an even layer and pour the egg mixture over the chard. Scatter the remaining chard mixture over the egg and sprinkle the remaining 1/2 cup of the cheese on top.

Bake the quiche until the top is brown and the center is set, 35 to 40 minutes. If the crust is browning too quickly, you can cover the edges of the crust with foil to prevent burning. Let the quiche cool for 10 minutes before serving. Garnish with the thyme and more ground black pepper.