Preheat the oven to 375 (F) -- this is a 50 degree (F) increase from the recipe's original bake temperature of 325 (F).
Put 1 cup flour, scant ¾ cup sugar, 1 teaspoon baking powder, pinch of salt, and 3 Tablespoons unsalted butter in a freestanding electric mixer with a paddle attachment (or use a handheld electric whisk) and beat on slow speed until you get a sandy consistency and everything is combined.
Mix the ½ cup plus 1 Tablespoon coconut milk and 1/2 teaspoon vanilla extract in a separate bowl, then beat into the flour mixture on medium speed until well combined.
Add the egg and beat well, scraping any unmixed ingredients from the side of the bowl with a rubber spatula.
Divide the chopped pineapple between the paper cases. Spoon the cupcake batter on top until two-thirds full and bake in the preheated oven for 20-25 minutes, or until light golden and the cake bounces back when touched.
Let the cupcakes cool slightly in the pan before turning out into a wire rack to cool completely.