Place the sugar, butter and flour into the bowl of a food processor (I use a mini one). Pulse/process until a dough forms.
Use a weighing scale to divide the dough in half, then place each half into a separate bowl. Knead the freeze dried strawberry powder and ground pink peppercorns into one of the dough halves, then knead the matcha powder and vanilla bean paste into the other.
Divide each ball of dough into 3 equal pieces. Then, divide 2 of the 3 balls in half, so that you are left with 1 large ball and 4 smaller, equal balls of each colour.
Use your hands and a bench scraper (or a clean metal ruler/anything that can be used to square off the edges of the dough) to form each of the smaller balls into short, rectangular logs (the cross section should be about 1 cm x 1 cm) of the same length. You should end up with 4 green logs and 4 pink logs.
Press one pink log alongside one green log. Make sure they are stuck together, but try not to distort the shape too much. Repeat this for the remaining logs.
Press one pair of logs on top of another, positioning them so that the top green section sits on the bottom pink section and vice versa. Repeat this for the second pair of logs, so that you end up with two larger, rectangular logs with a 2x2 checkerboard pattern.
Roll out one of the larger dough balls between two sheets of baking paper. Don't add any flour at this stage. Aim to roll the dough into a rough rectangle, slightly wider than the length of one log and a little over 8cm long, so that it can be used to wrap all the way around one of the logs.
Peel off the top sheet of baking paper, then place one of the logs on top of the rolled out dough, at one end. Use a sharp knife to trim off the excess dough along the back of the log and down both sides, flush with the edges of the log.
Using the baking paper to help you, roll the log down the length of the rolled out dough, pressing gently to help the dough stick to itself, until it is completely covered, like a Battenberg. Trim off any excess dough, then repeat the process for the second log with the final, large ball of dough (in the other colour).
Any offcuts can be rolled together and pressed into little round biscuits to be baked alongside the checkerboard biscuits later.
Wrap both biscuit logs tightly in clingfilm, then place them into the fridge to chill for 2 hours. This will firm them up, so that you can slice them without distorting the checkerboard pattern.
After 2 hours, preheat the oven to 180°C (conventional oven, not fan). Slice each log into biscuits about 5-7mm thick, then space them out on a baking tray lined with baking paper. The biscuits won't spread very much, so you don't need to leave heaps of room between them.
Bake the biscuits for 6-8 minutes, until just starting to turn golden around the edges. Allow them to cool on the tray for 5-10 minutes, then carefully transfer to a wire rack to finish cooling before serving. The biscuits can be stored in an airtight container at room temperature for up to 3 days before they start going a little soft.