Vanilla Brownie Cake Recommended Product: BLACK+DECKER WiFi Slow Cooker. Prep Time: 10 min Cook Time: 4 hr Ready In: 4 hr 10 min Serves: 12 Ingredients: 18.4oz Box Brownie Mix 15.25oz Box Vanilla Box Mix Directions: Prepare each box mix according to package directions. Grease the slow cooker with cooking spray and pour in the vanilla cake mix. Dollop the brownie into the vanilla cake. Using a small silicone spatula, swirl the brownie mix into the vanilla cake mix. Place the lid on the slow cooker, placing a paper towel under the lid to catch any condensation. Cook for 2 hours on high, or 4 hours on low, or until the center of the cake is set. Serve warm with ice cream.