Greek Yogurt Brownies

Name: Greek Yogurt Brownies
Prep time: 15 min
Cook time: 30 min
Total time: 45 min
Cuisine: American
Ingredients: Vegetable oil or nonstick cooking spray (for greasing); 1.5 ounces bittersweet chocolate (chopped, 70% cacao); 113 grams unsalted butter (cut into 1-inch pieces); 24 grams dutch-process cocoa powder; 1 teaspoon instant espresso (or espresso powder); 100 grams eggs (from about 2 large eggs); 267 grams granulated white sugar; 4 ½ ounces greek yogurt or skyr (from about 1 single serve container, preferably coffee-flavored); 6 grams pure vanilla extract; 1/2 teaspoon kosher salt; 92 grams all-purpose flour; 80 grams semi-sweet chocolate chips; Flaky salt (optional, for topping)