Preheat oven to 175 degrees C. Grease 10 x 3/4 cup (180ml) mini cake moulds. Drain pineapple rings, reserving 1/4 cup juice.
Combine flour and baking powder in a small bowl.
Combine 175g melted butter and caster sugar in a large bowl. Beat with an electric mixer on medium speed until well blended, about 3 minutes. Add eggs one at a time. Mix in reserved 1/4 cup pineapple juice, 1/2 cup coconut cream, milk, 1 tablespoon coconut extract and vanilla extract. Add flour mixture gradually, mixing until batter is smooth.
Mix brown sugar and 75g melted butter together in a bowl until smooth. Spoon into the bottom of the cake moulds. Place 1 pineapple ring in each mould. Place 1 maraschino cherry in the centre of each ring.
Divide batter among cake moulds using an ice cream scoop.
Bake in the preheated oven until a toothpick inserted into the centre comes out clean, about 20 to 22 minutes. Cool to room temperature, about 20 minutes. Run a knife around the rims to loosen cakes; invert gently onto a plate.
Pour cream into a chilled metal bowl. Add cream of tartar. Beat with an electric mixer until almost holding peaks. Add icing sugar gradually, continuing to beat until soft peaks form. Fold in pineapple juice, coconut cream and coconut extract.