Preheat oven to 180°C. Line medium sized 12 cup muffin tray with square pieces of grease-proof baking paper.
Wash the feijoa whole (skin on) then cut off the bud end, leaving skin on. Slice into chunks then blitz in a food processor until resembles a chunky salsa. Measure one cup.
In another bowl cream butter and sugar, then mix in eggs and sour cream. Stir through chunky feijoa puree.
Sift flour, mixed spice and baking powder into the wet mix. Fold through well.
Spoon a generous spoonful of mix into each muffin mould. Cut a dab of cream cheese, dot it in the middle, top with more mix and a final dot of cream cheese (therefore, one dab in the muffin, one on top).
Bake for 20 minutes until golden brown.
Demolish without guilt.