Upside-Down Apple and Walnut Cake

This is a perfect afternoon tea cake that I was quite pleasantly surprised with.  Cakes cook so much faster in the microwave than the oven, so it's perfect if you're pressed for time.  I thought it would come out a bit dry being microwaved, but I found the caramel topping made it nice and moist.  It's perfect served with some extra walnuts sprinkled on top!

Ingredients
Melted butter, to grease
160g butter, at room temperature
200g (1 cup, firmly packed) brown sugar
1 300ml container thin cream
2 apples, peeled, halved, cored, cut lengthways into thin slices
1 tsp vanilla essence
2 eggs, at room temperature
225g (1 1/2 cups) self-raising flour
1 tsp ground cinnamon
55g (1/2 cup) walnut halves, chopped

Method
Brush a 7cm-deep, 20cm (base measurement) microwave-safe ring container with the melted butter to lightly grease. Line the base with non-stick baking paper. (I used my Tupperware Kugelhopf and greased it with butter but didn't line it).

Combine 60g of the butter, 100g (1/2 cup, firmly packed) of the sugar and 2 tbs of the cream in a medium, heatproof microwave-safe bowl. Heat, uncovered, on High/800watts/100%, stirring every minute, for 2 minutes or until the sugar dissolves and the sauce is smooth. Set aside.

Spread the apple slices over a large microwave-safe plate so they are no more than 2-3 deep. Cover with plastic wrap and cook on High/800 watts/100% for 1-2 minutes or until just tender when tested with a skewer. Drain any excess moisture from apples and then gently stir apples into caramel sauce. Spread apples and sauce evenly over base of ring container.

Place the remaining butter, remaining sugar and vanilla essence in a medium bowl. Use an electric beater to beat on high speed until well combined. Use a wooden spoon to mix the eggs in, 1 at a time, until well combined.

Sift the flour and cinnamon together into a bowl. Use the wooden spoon to gently stir the flour mixture and 60ml (1/4 cup) of the remaining cream into the butter mixture in 2 batches. Add walnuts and stir gently to combine. Spoon mixture evenly over the apple mixture in the ring container.

Place the container on a microwave-safe rack or upturned plate to elevate it about 2cm above the microwave turntable. Cook, uncovered, on Medium/500watts/50% for 9-10 minutes or until the cake looks cooked but the surface (in the centre) is still a little sticky. Stand for 5 minutes or until a skewer inserted into the centre of the cake comes out clean.

Meanwhile, lightly whip the remaining cream until soft peaks form.

Turn the cake onto a serving plate. Serve warm or at room temperature with the whipped cream.