Melt 1 tablespoon butter in a large skillet over medium-high heat. Add 4 heads baby bok choy (halved lengthwise) and cook until browned, 3 minutes. Flip and cook 2 more minutes. Season with kosher salt and pepper. Stir in 1 tablespoon butter, 1 chopped garlic clove and 8 thyme sprigs; remove from the heat. Top with flaky salt.