Potato focaccia with black garlic butter

Combine 500ml warm water and yeast in a jug. Stand in a warm place until foamy (10 minutes), then stir in oil.

Meanwhile, place flours, dried saltbush, mashed potato and 10gm fine salt in the bowl of an electric mixer; stir to combine. Using a dough hook attachment, gradually mix in yeast mixture on low speed until combined, smooth and elastic (5-7 minutes); dough will be sticky and wet. With oiled hands, shape into a ball and place in a large, oiled bowl. Cover with a clean damp tea towel and leave to rise until doubled in size (about 1 hour).

Preheat oven to 160˚C fan-forced. For black garlic butter, place garlic and oil 

on a small oven tray; roast until lightly golden and soft (30 minutes). Process roast garlic, oil and black garlic in a small food processor to a paste; cool to room temperature; press through a sieve. Place butter in the bowl of an electric mixer; whisk on high speed until light and fluffy (5 minutes). Add garlic purée, season to taste and whisk to combine. Transfer black garlic butter to an airtight container and serve at room temperature. It will keep refrigerated for up to 3 months.

Grease and line the base of a 5cm-deep, 26cm x 32cm baking tray with baking paper. Using oiled hands, knock back dough, transfer to tray and press over base. Loosely cover dough with a clean damp tea towel and leave to prove until doubled in size (about 1 hour).

Preheat oven to 240˚C fan-forced and set rack at the bottom one third of oven. Using your fingertips, gently dimple dough with your fingers, pressing to make small indents. Drizzle with more olive oil and scatter with sea salt flakes, fennel seeds, rosemary, and saltbush. Bake until golden brown, rotating tray halfway (20-25 minutes). Transfer to a wire rack; drizzle liberally with more olive oil and stand for 10 minutes. Using paper as an aide, lift focaccia onto a wire rack and cool for 10 minutes. Serve with black garlic butter.