Preheat the oven to 180°C conventional, or 170°C fan-forced. Prepare a 20 cm springform tin. If using a good-quality non-stick tin, line the base with baking paper. Otherwise, grease and line the base and sides.

Weigh the plain flour and baking powder into the Thermomix bowl. Mix 3 sec/speed 4, then transfer to a bowl and set aside.

Cut the pears into 1 to 2 cm cubes and set aside.

Without washing the Thermomix bowl, add the butter, brown sugar, plain flour and cinnamon for the crumble topping. Mix 5 sec/speed 7.

Add the pear and almonds. Mix 3 sec/reverse/speed 2. Transfer the crumble topping to a bowl and set aside.

Without washing the Thermomix bowl, add the cold cubed butter, caster sugar, vanilla and almond extract. Mix 20 sec/speed 4.

Scrape down the sides of the bowl and use the spatula to lift any butter mixture from underneath the blades. Insert the butterfly whisk and mix for a further 20 sec/speed 3.5. This extra scrape is worthwhile when using cold butter, as some can stick beneath the blades rather than becoming part of the creamed mixture.

Set the Thermomix to speed 3 and add the eggs through the hole in the lid, one at a time, allowing about 6 seconds between each egg.

Add half the flour mixture and mix 3 sec/speed 2. Add the sour cream and mix 3 sec/speed 2.

Add the remaining flour mixture and mix 5 sec/speed 3.5, or just until combined. Scrape down the bowl if needed and give the mixture a final fold through with the spatula.

Spoon the batter into the prepared tin and spread it level. Sprinkle the pear and almond crumble evenly over the top.

Bake for about 60 minutes, checking from 50 minutes onwards. The exact time will vary with your oven and tin. The cake is ready when a skewer inserted into the cake portion comes out clean or with a few moist crumbs.