Preheat your oven to 350°F (175°C). Gather all your ingredients: crushed pineapple, brown sugar, butter, flour, sugar, baking powder, milk, eggs, and vanilla extract.

In a small saucepan over medium heat, melt the butter and add the brown sugar, stirring until it forms a thick syrup. Pour this mixture into each muffin cup or ramekin, then layer some crushed pineapple on top.

In a large mixing bowl, combine the flour, baking powder, and salt. Whisk until well blended.

In another bowl, mix the sugar, eggs, vanilla extract, milk, and pineapple juice until smooth. Combine with the dry ingredients and mix until just combined.

Pour the batter over the pineapple topping in the muffin cups. Bake for 20 minutes or until a toothpick inserted comes out clean.

Let the cakes cool for a few minutes before inverting onto a plate. Serve warm or cold.