Bombe Vincent

1.For brown butter, melt butter in a saucepan over medium-high heat, then add milk powder and whisk until milk solids start to colour, and the butter foams and smells nutty (4-5 minutes). Strain mixture through a fine sieve (discard liquid), then leave milk solids to dry and cool on a few changes of absorbent paper.

2.Preheat oven to 180C. Beat softened butter and egg yolks until pale and fluffy (3-5 minutes), add brown butter solids and flour, and mix slowly by hand. Whisk eggwhites and sugar in an electric mixer to form firm peaks, fold into flour mixture, then spoon into an 18cm x 26cm lamington tin lined with baking paper and bake until just cooked (8-10 minutes). Cool, then press each of 6 lightly oiled 7.5cm-diameter x 5cm-high stainless-steel ring moulds into the sponge, retaining in the moulds, and place on a tray lined with baking paper in the freezer to chill (30 minutes).

3.For walnut and coffee parfait, preheat oven to 180C and toast walnuts on a baking tray in oven until golden (5-7 minutes). Set aside to cool, then finely chop. Whisk egg yolks and half the icing sugar until creamy and pale (4-5 minutes). Divide mixture into 2 bowls, add Nocino and chopped walnuts to one bowl, and ground coffee and coffee extract to the other. Whisk remaining sugar with the eggwhites in an electric mixer until soft peaks form (4-5 minutes). Whip cream until soft peaks form. Equally divide eggwhite and cream between the 2 bowls and fold together the contents of each. Refrigerate until required.

4.Remove ring moulds from freezer and parfait mixtures from fridge. Half-fill each mould, on top of sponge bases, with walnut parfait mixture, smooth tops, then top with coffee parfait mixture and smooth tops. Cover each ring mould with plastic wrap and freeze until firm (at least 6 hours or overnight).

5.For Italian meringue, dissolve sugar in 2 tbsp water in a saucepan over medium-high heat and continue to boil until the temperature reaches about 115C (3-4 minutes). At this stage begin to whisk eggwhites in a mixer until soft peaks form. When syrup reaches 121C, remove from heat and pour in a steady stream down the side of the bowl into the eggwhites while continuing to beat at medium speed until the mixture has cooled and syrup is incorporated (5-7 minutes). Transfer to a piping bag fitted with a 1cm fluted nozzle and set aside.

6.Preheat oven to 250C. Remove the iced parfaits from their moulds by running a knife carefully around the inside of each to loosen, then push through from the cake end and place closely together on a foil-lined baking tray. Working quickly, cover parfaits with piped meringue and bake in the oven for 2 minutes to brown; if necessary, finish colouring meringue under a grill or with a blowtorch and serve immediately.