Soak the gelatine in 120 ml cold water for 5–10 minutes to soften.
In a medium saucepan, combine 400 g caster sugar, 80 ml water, and 2 tbsp glucose or corn syrup. Heat gently until the sugar dissolves, then boil to 118°C (soft-ball stage).
Remove from the heat and stir in the softened gelatine with its soaking water until melted and fully combined.
Transfer to a large bowl or stand mixer. Whip on high speed for 8–10 minutes until the mixture is thick, white, and fluffy. Beat in the vanilla extract.
Divide the mixture into two bowls. Tint one portion pink and leave the other white.
Line a square or rectangular tin with non-stick paper and dust with a 50:50 mix of icing sugar and cornflour.
Spoon alternate layers or stripes of white and pink marshmallow into the tin. Smooth the top and dust again with the sugar-cornflour mix.
Leave to set at room temperature for 4–6 hours or overnight.
Turn out onto a board, dust again, and cut into strips about 2 cm wide to resemble bacon slices.