Method

• 1.
  For the frangipane, beat the butter and sugar in a stand mixer fitted with the paddle attachment on high speed until pale and fluffy. Add the eggs, one at a time, waiting until the first is fully incorporated before adding the next and scraping down side of bowl occasionally between additions. Add vanilla with the second egg. With the mixer on low speed, add the buttermilk, flour, almond meal and a pinch of fine salt. Scrape side of bowl down well, giving it a final mix with a spatula to ensure all ingredients are well incorporated. Chill for 1 hour to firm up.
• 2.
  Meanwhile, for the topping, place butter in the clean bowl of a stand mixer fitted with the paddle attachment and beat on high speed until pale and creamy. Add the flour, custard powder, icing sugar and 100s and 1000s and mix on low speed until ingredients start to bind together, forming a chunky crumble consistency. You’re looking for small pebble-sized pieces of crumble. Transfer to a container and chill until required.
• 3.
  For the milk syrup, place all ingredients in a small saucepan and stir over medium heat until the sugar dissolves. Set aside and keep warm.
• 4.
  Preheat oven to 200°C/180°C fan-forced. Line a large baking tray with baking paper.
• 5.
  Using a large serrated knife, cut the croissants in half horizontally. Brush the cut sides generously with warm milk syrup. Spread a generous amount of frangipane on the bottom half of each croissant. Generously scatter frangipane with 100s and 1000s and replace croissant tops, gently securing each top to the base. Finish off each croissant by spreading a strip of frangipane across the top, then press chunks of crumble topping into the frangipane strip, all along the top of croissant (see notes).
• 6.
  Place on a prepared tray and bake for 20-25 minutes, until the frangipane inside is set and the crumble is golden. Set aside to cool completely. Dust with icing sugar.
• 7.
  For the buttercream, in a stand mixer fitted with the whisk attachment, whisk the egg whites on high speed to soft peaks. Meanwhile, in a small saucepan, bring the sugar and 1/4 cup (60ml) water to the boil, stirring to dissolve the sugar and create a syrup. Using a sugar thermometer, take the syrup to between 115°C and 118°C. Remove from the heat and, in a slow and steady stream, carefully pour the sugar syrup into the egg whites while they’re whisking on low speed. Increase the speed to high and whip until the bowl has cooled down to room temperature. Gradually add the butter, two or three pieces at a time, whisking well between each addition to ensure that it’s fully incorporated. Add the lemon juice and vanilla, and beat well to combine. Transfer to a piping bag fitted with a 1cm star nozzle.
• 8.
  Pipe 6 or 7 kisses of buttercream randomly over the top of each pastry, then garnish the buttercream kisses with 100s and 1000s. (It’s important that this is done when the croissants are completely cool, otherwise the buttercream will melt.) Serve.