Pastry cream

1. Dissolve cornstarch in 1?4 cup of milk in a mixing bowl.
2. Combine the remaining 3/4 cup milk with the sugar in a small to medium heavy based saucepan on medium-low heat, bring to the boil, whisking occasionally so it doesn’t form a skin on top or scald on the bottom, then remove from heat.
3. Beat the egg yolks and vanilla into the cornstarch mixture. Pour 1/3 of the hot milk into the egg mixture, whisking constantly (this tempers the eggs so they don’t cook before they are mixed into the custard).
4. Return saucepan to low heat and pour the egg mixture back into the milk in a stream while continuously whisking.
5. Continue whisking until the mixture comes to a boil and thickens, about 2 minutes. Remove from heat.
6. Scrape into a bowl and press a piece of plastic wrap firmly against the surface. Cool to room temperature then refrigerate until ready to use.
7. When ready to fill cake, whip the cream to stiff peaks and fold into pastry cream.

Cake

1. Note: if using active dry yeast instead of instant, activate it in the milk for five minutes before proceeding.
2. Whisk together flour, sugar, yeast and salt in a large bowl, then add mascarpone, egg and milk and mix to combine. Knead with dough hook on low speed or by hand for 10 minutes, until you have smooth dough. It will be very soft and sticky.
3. Scrape dough into a ball, cover bowl with plastic wrap and let rise in a warm place for about an hour, until doubled in volume.
4. Tip the dough into a lightly greased cake pan, 20 – 25cm (8 – 10?) in diameter. Press the dough out into the pan with damp fingertips. Cover with plastic wrap and let rise in a warm place for 30 minutes.
5. Preheat oven to 180°C (360°F) while you prepare the topping.

Topping

1. In a medium bowl, whisk together sugar, flour and cinnamon. Add cold butter and, with your fingers, mix all ingredients until you have the texture of soft breadcrumbs.
2. Brush the cake with egg wash and sprinkle with the topping.
3. Bake in centre of oven for about 25 minutes, until golden.
4. Cool cake in pan for ten minutes then transfer to a wire rack and allow to cool completely before filling.
5. Use a large serrated knife to cut the cake into two layers, spread the pastry cream onto the bottom half and replace the top.