Line 13×9-inch (3-quart) baking dish with cooking parchment paper; spray with cooking spray. Set aside.
In 4-quart saucepan, melt butter over medium heat. Add marshmallows. Stir with wooden spoon or rubber spatula until melted. Add almond extract. Reduce heat to low; stir in cereal and almond paste until evenly coated. Pour into baking dish. Use greased rubber spatula or greased hands to press mixture firmly and evenly in dish. Refrigerate 20 minutes.
Remove from baking dish. Use heart-shaped cookie cutter to cut into hearts. Scraps can be rerolled with greased rolling pin.
Microwave chocolate in microwavable bowl uncovered on High in 30-second increments, stirring after each. Dip hearts halfway into chocolate; sprinkle with sprinkles, and place back on parchment paper. Place in freezer a few minutes until chocolate hardens.