- Combine oats, shredded coconut, flour, sugar, and salt in medium bowl
- Melt 4 tablespoons butter in medium cast iron skillet over medium heat. Stir in oat mixture. Cook, stirring, until toasted and crumbly, about 3 minutes. Transfer back to medium bowl and wipe out skillet.
- Melt remaining 4 tablespoons butter in now empty skillet over medium heat. Add pineapple slices and cook until bottoms are browned and sticky, 3-5 minutes.
- Flip and cook until other side is caramelized, about 3 additional minutes. Be careful not to burn pineapple -- that doesn't taste awesome.
- Top with crumble and serve with ice cream.