Method

• 1.
  For the caramel, place the glucose and sugar in a small saucepan over medium heat and cook, swirling pan frequently, for 8-10 minutes until sugar has melted and a deep golden caramel forms (don’t worry if the sugar crystallises halfway; continue swirling the pan so it melts completely and becomes smooth). Reduce heat to low.
• 2.
  Meanwhile, place espresso powder, cream and vanilla in a separate small saucepan over high heat, whisking constantly, until espresso powder dissolves and mixture comes to the boil.
• 3.
  Carefully pour the hot cream mixture over the caramel in pan (it will splatter), stirring to combine. Cook, stirring constantly, over low heat until mixture reaches 104°C on a sugar thermometer, is completely smooth and any crystallised sugar has dissolved. Stir in 1/2 tsp fine salt. Remove pan from heat and cool to 50°C, then stir in butter until melted and combined. Transfer espresso caramel to a small container, cover and freeze until almost ready to assemble.
• 4.
  For the crumble, use hands to combine ingredients in a medium bowl, then knead lightly until smooth. Roll between sheets of baking paper to 2mm thickness, then transfer to a large baking tray and freeze for 30 minutes until firm.
• 5.
  Preheat oven to 220°C/200°C fanforced. Grease two large baking trays and line with baking paper.
• 6.
  For the choux pastry, crack the eggs into a measuring jug (do not mix).
• 7.
  Place the butter, milk, 1/2 tsp fine salt and 1/3 cup (80ml) water in a medium heavy-based saucepan over medium-high heat. Cook, swirling pan occasionally, until butter has melted, then bring mixture to the boil. Immediately add the flour and beat vigorously with a wooden spoon for at least 2 minutes until mixture forms a smooth ball that pulls away from sides of pan. Reduce heat to low and beat mixture for at least 1 minute to dry out dough.
• 8.
  Remove from the heat and stand for 1 minute to slightly cool. Add the eggs, one at a time, beating thoroughly with a wooden spoon until combined (dough should be shiny and smooth).
• 9.
  Transfer choux dough to a large piping bag fitted with a 1cm plain nozzle. Pipe 10 roughly 6cm rounds onto the prepared trays, 5cm apart, to allow enough room for them to double in size.
• 10.
  Use a 6cm round cookie cutter to cut rounds of the frozen crumble. Rest a crumble round on top of each choux dough, lightly pressing down.
• 11.
  Bake for 25 minutes until pastries are puffed, deep golden and feel light for their size. Remove and cool on trays.
• 12.
  For the mascarpone cream, place sugar and yolks in a stand mixer fitted with the whisk attachment. Whisk on medium-high speed for 5 minutes, scraping down side of bowl occasionally, until very pale and fluffy and sugar has dissolved. Add cream. Whisk until firm peaks form, then fold through mascarpone until just combined. Transfer to a large piping bag fitted with a 1cm plain nozzle.
• 13.
  To assemble, remove espresso caramel from the freezer and stand at room temperature for 15 minutes. Stir well with a teaspoon. Cut tops off choux pastries. Pipe mascarpone cream into choux, then drizzle with espresso caramel. Replace choux pastry tops and serve.