1Mix up a batch of same-day focaccia dough and let it rest for 15 minutes.
2Incorporate the frozen grated garlic butter into the dough during two sets of stretch and folds; scatter half for the first fold, wait 15 minutes, and repeat with the second half.
3Let the dough rest at room temperature for 1 to 1.5 hours.
4While the dough rests, in a small frying pan, melt together the salted butter, minced garlic, and garlic granules over medium heat.
5Simmer for 1 to 2 minutes and then stir in the chopped parsley.
6On a clean worktop, brush some of the prepared garlic butter into a rectangle the size of your baking tray (roughly 9x13 inches or 23x33 cm).
7Tip the dough onto the butter and use buttered fingers to gently pull the dough into a 9x13 inch rectangle with an even thickness.
8Cut the dough into 15 as evenly sized as possible pieces by cutting into 3 rows, then into 5 rows.
9Coat each piece with the garlic butter and place into the parchment-lined tray in a 3x5 formation, saving a small amount of garlic butter for later.
10Cover and proof at room temperature for 1 to 1.5 hours.
11Scatter half of the grated mozzarella and half of the grated Parmesan over the dough and dimple it in.
12Bake on the lowest rack of the oven at 220C/430F for 12 minutes.
13Remove from the oven and sprinkle over the remaining cheese, reserving a couple of tablespoons of Parmesan for garnish.
14Return to the oven to finish baking for another 8-10 minutes, or until golden.
15Brush over the remaining garlic butter and scatter over the reserved Parmesan cheese.