Make the matcha cake:

• Prepare the matcha chiffon cake batter according to the recipe instructions.
• Transfer the cake batter to a 13" by 18" baking sheet lined with parchment paper and smooth the surface with an offset spatula.
• Tap the pan a few times to release any trapped air bubbles.
• Bake the cake for 8-10 minutes at 375°F/163°C, or until the top of the cake is dry and springy to the touch.
• Remove from the oven and let it cool completely on a wire rack.

For key visual steps, refer to body of the blog post.

Make the vanilla ice cream:

• Pour the cold heavy cream into a large bowl. Set aside.
• Separate 6 egg yolks from the egg whites and place the egg yolks into a heat-safe bowl. (Refrigerate or freeze the egg whites for later use).
• In a bowl, whisk together the egg yolks with sugar, vanilla extract, vanilla bean paste (if using), pinch of salt and set aside.
• Add the milk to a saucepan and heat over low-medium heat until scalding hot.
• While whisking the egg yolk mixture, gradually pour in the warmed milk (known as tempering the eggs).
• Pour the mixture back into the saucepan and cook over low-medium heat, until the custard thickens. When you can draw a line on the back of a spatula, the custard is ready.
• Pour the custard through a sieve into the cold heavy cream.
• Give the mixture a stir and cover with a lid/plastic wrap.
• Place into the fridge to chill for at least 6-8 hours, or overnight.
• The next day, churn the ice cream according to your ice cream maker's instructions.
• Transfer the churned ice cream to a 9" by 13" baking tray lined with parchment paper and use an offset spatula to smooth out the surface.
• Freeze the ice cream for at least 6-8 hours, or until frozen solid.

Assemble:

• Flip the matcha cake upside down so that the parchment layer is on top.
• Gently peel off the parchment paper from the cake.
• Slice the cake in half (widthwise) so you end up with two 9" by 13" pieces.
• Flip and place one half of the cake with the browned side facing up (this will be the interior).
• Remove the parchment paper from the ice cream slab.
• Carefully position the ice cream over top of the browned side half of the cake.
• Top the ice cream with the other cake, with the green (not brown) side facing up.
• Cover with a lid/plastic wrap and place into the freezer to freeze for a few hours until firm.
• When ready to serve, trim off the edges using a clean, serrated knife and cut into bars or squares to your liking.