Place a rack in center of oven; preheat to 350°F. Mist a 9-inch square glass baking dish with cooking spray. Stir cherries, 2 Tbsp. sugar, kirsch and juice in baking dish to combine. Roast until bubbly and juices have thickened, about 15 minutes. Transfer to a bowl and let cool completely.
Mix cocoa and 1/4 cup sugar in a bowl. Whisk in coffee until sugar and cocoa have dissolved. Let stand for 5 minutes. Stir in milk and extracts; pour into another 9-inch square baking dish. Freeze until completely frozen, about 1 hour, scraping frozen crystals from edge of pan with a fork every 15 minutes.
When ready to serve, scrape granita into chilled glasses, breaking up any large pieces with a fork. Top with cherries.