Instructions

• Preheat oven to 350°F. Line an 8-by-8-inch baking pan with aluminum foil (leave an overhang for easy lifting) and spray the foil with cooking spray; set aside.
• Place ½ cup unsalted butter (1 stick) in a large, microwave-safe bowl and microwave on high about 1 minute, until melted. Let the butter sit for a few seconds so it stops bubbling.
• Add 1 large egg to the melted butter and whisk immediately so the egg warms gradually and does not scramble.
• Add 1 cup packed light brown sugar and 1 tablespoon vanilla extract to the bowl and whisk until smooth.
• Add 1 cup all-purpose flour and a pinch of salt (optional) and stir just until combined; do not overmix.
• Turn the batter into the prepared pan and smooth the top lightly with a spatula.
• If needed so they will drizzle easily, warm the toppings briefly (hot fudge and caramel) until pourable. Evenly drizzle about 1/3 cup 10-Minute Homemade Hot Fudge over the batter.
• Evenly drizzle about 1/3 cup Homemade Salted Caramel Sauce over the batter.
• With the tip of a table knife, lightly swirl the hot fudge and caramel into the batter—leave some bare patches and avoid over-swirling.
• Bake for about 25 to 30 minutes. Test by inserting a toothpick into a bare patch; it should come out mostly clean or with a few moist crumbs but no raw batter. (Ignore the glossy, wet appearance of the fudge and caramel when testing.)
• Allow the blondies to cool in the pan for at least 30 minutes before lifting out on the foil overhang and slicing. Store airtight at room temperature up to 1 week, or freeze up to 6 months.