Combine the warm water and the yeast. Set aside.
1.25 cups warm water, 2 tsp active dry yeast
To a large bowl add the flour, salt and mashed potatoes and give it a good mix. Add the water yeast mixture and combine with the flour until a shaggy sticky dough forms. Drizzle a little olive oil around the sides of the bowl to prevent sticking.
2.5 cups all purpose flour, 1 cup mashed potatoes, Olive oil as needed, 1 tsp sea salt
Cover the bowl with plastic wrap or parchment paper and a tea towel then place in a draft free area between 75 - 78”F degrees for 2 to 3 hours until almost doubled in size. (The cold oven is a great place for this). (If you like you can also place it in the fridge overnight for a slow rise then bring to room temperature for 1 or 2 hors before baking).
Prepare a 9 inch spring form pan lined with parchment paper. Very lightly oil the sides of the dish then place it on a baking sheet.
Olive oil as needed
Dump the focaccia dough into the spring form pan. Use your hand and press the top of the dough to deflate it and create dimples. It will be sticky, just roll with it! Cover again and allow it to rise a second time for about one hour or so; again timing is forgiving, I just want the dough to spring back and get fluffy.
Meanwhile preheat your oven to 400”F.
Scrub and rinse a golden potato and using a mandoline slicer (with a hand guard) thinly slice the potato on the thinnest paper thin setting. Place the slices in a bowl and cover with cold water. Transfer the potato slices to a lint free tea towel and dry as much of the moisture as possible but don’t stress too much about it.
1 golden potato
Place the slices of potatoes on top of the focaccia dough overlapping each other. Sprinkle with the rosemary leaves, freshly cracked black pepper (a pinch of red chili flakes if you fancy some heat) and drizzle with olive oil. Sprinkle the top with a good pinch of sea salt flakes and place in the preheated oven 35 minutes until golden brown on top.
1 golden potato, 1 sprig rosemary, Sea salt flakes, Olive oil as needed, Black pepper to taste
Transfer the bread to a cooling rack for a good 15 minutes. Run a butter knife alongside the spring form pan to release any dough that might have stuck. Open the spring form pan and remove. (The sides of the focaccia should look beautifully golden brown with a perfect crispness while the center is fluffy and moist from the mashed potatoes.)
Slice into wedges (using a bread knife is best) and serve with a side of basil pesto, sun dried tomato pesto, tapenade, thick tomato sauce or roasted veggie spread.