Duck-fat potato Focaccia bread アヒルの脂肪入りジャガイモフォカッチャ

This focaccia bread is based on a recipe from a new cookbook called "A good day to bake".  We got the cookbook at the recommendation for my wife's sister. She read a good review of it in the New York Times The original recipe calls for goose fat. But we did not have goose fat. We did, however, have frozen duck fat (leftover from making duck confit). This is essentially a recipe for the standard focaccia bread but instead of olive oil, it uses duck (or goose) fat plus thinly sliced potatoes and rosemary as toppings. It came out nicely with the potato almost like potato chips (see picture below).

Ingredients:
450 g (3 and 1/4 cups) bread flour
7gram instant yeast
300 ml (1 1/4 cup of water )(or a bit more or less depending on the dough consistency)
1 tsp Kosher salt
80g duck fat or goose fat
1tsp sugar

Topping
3-4 baby red potato, eyes and skin removed and sliced thinly (I used a Japanese mandoline "Benriner")
A few sprigs of fresh rosemary, leaves removed and roughly chopped.
More duck fat to coat the potato slices.

Directions: (Since the amount of flour and water is the same as my focaccia bread, I used my usual procedure of the food processor fitted with a kneading blade instead of a stand mixer or by hand).

Add the flour, salt, sugar, yeast and duck fat in the food processor. Pulse it to roughly mix. Turn on at low speed and drizzle in the water until a dough ball forms above the kneading blade (the amount of the water may need to be adjusted). Let it stand for 5 minutes so that the moisture distributes evenly. Turn on the food processor to low speed and knead the dough for 1 minute. Take the dough out onto a floured board, and knead 5-7 minutes and make a tight ball. Put a small amount of olive oil (or duck fat) in a bowl, place the dough ball turning a few times to coat in the oil/fat. Cover the bowl with plastic wrap and let in rise until the volume doubles (1-2 hours) (I used a bread proofing box at 80 F). Place the dough on a 38x26cm(15x10 1/2 in) lightly oiled (I used olive oil but duck and goose fat can be used) baking pan, spread to fill the pan (may need 5-10 minutes rest to relax the dough). Cover it with a plastic wrap and let it rise for 45-60minutes (the baking pan did not fit into my proofing box, so I just put it on the top of the box without the lid. Preheat the oven to 375F (the original recipe calls for 435F but to me that is too hot since we do not like a hard crust).

Coat the dough surface with oil (I used olive oil) and make deep dimples using your fingers. Spread the duck fat coated potato slices and roughly chopped fresh rosemary leaves (see below).

Bake it 25-30 minutes or until the surface is brown/golden (see below picture). Take it out on the wire rack and let it cool.

Thinly sliced potato adds an interesting crunch texture almost like potato chips (but not quite that crispy). We could taste the rosemary but not the duck fat.

We had similar experience with the pan baked potato with duck fat. Somehow the duck fat does not add much of the flavor. I would rather use olive oil to reduce the amount of saturated fat. In any case, this is a good focaccia but I will make it without duck or goose fat next time.