For Waffles: Position rack in middle of oven. Preheat oven to 200°F/60°C. Set a rack on a rimmed baking sheet pan and set aside.

Combine the milk and lemon juice in a measuring cup and allow to sit for 5 minutes to thicken.

Whisk flour, black cocoa powder, brown sugar, baking powder, baking soda, and salt in a large bowl. Make a well in the center of the dry mixture and add the beaten eggs, thickened milk, oil, and vanilla. Whisk together until batter is very well combined and smooth.

Heat a waffle iron until very hot; lightly coat with nonstick spray. Working in batches, cook waffles until cooked through. Transfer to prepared wire rack and keep warm in oven until ready to serve.

Serve waffles with butter and maple syrup or a sprinkling of confectioners’ sugar or make ice cream sandwiches!

To Make Ice Cream Sandwiches: For every ice cream sandwich you will need two cooled heart shaped waffles, 1/2 cup (120 ml/66 g) ice cream and 1/4 ounce (7 g) of melted dark chocolate.

Soften the ice cream a little bit and scoop it out onto a cutting board. Press it down to a thickness of about 3/4 inch (2 cm). Cut out heart shapes using cookie cutter the same size as the hearts, or use a paring knife to cut out heart shapes. Use a broad spatula (like a pancake turner) to scoop up each heart and place on one heart shaped waffle, topping with second waffle and gently squeeze together. Smooth the sides of the ice cream, if necessary, with a small offset spatula. Freeze until solid on a tray or pan. Drizzle with melted chocolate, if using, and freeze again until chocolate is firm then individually wrap ice cream sandwiches in plastic wrap. Freeze for up to 1 week. Let them soften outside of freezer for a couple of minutes before serving.