Pineapple:

2 tablespoons unsalted butter

1/2 cup lightly packed dark brown sugar

One 20-ounce can sliced pineapple, drained and juice reserved

One 20-ounce can crushed pineapple, drained and juice reserved

Cake:

1 1/3 cups all-purpose flour

2 teaspoons baking powder

1/4 teaspoon fine salt

1/2 cup whole milk

2 teaspoons pure vanilla extract

1/4 cup reserved pineapple juice (from the cans)

3/4 cup granulated sugar

1/2 cup unrefined coconut oil

1 large egg