Roasting crushed pineapple with brown sugar creates a delicious flavoring for ice cream-seltzer floats.
Preheat oven to 425 degrees.
Place drained pineapple on a rimmed baking sheet and sprinkle with brown sugar. Cook until just golden, about 20 minutes. Transfer to a bowl; let cool completely.
Divide pineapple evenly among 8 serving glasses. Top with 2 teaspoons syrup and 2 scoops ice cream. Fill with club soda. Drizzle with remaining syrup.