Caramelized onion and potato galette

Cut the butter into tablespoon-size or slightly smaller pieces and keep it in the freezer until cold.

Pulse the flour, sugar, salt, grated parmesan and pepper in a food processor a couple of times to combine.

Add the butter and pulse until the pieces are between the size of quarters and nickels.

Tip into a bowl and flatten the bigger butter pieces into sheets between the fingers; break up any large chunks so they do not melt out of the galette.

Stream in the ice water while stirring lightly with a fork, just enough that the dough squishes together; it will look dry and hydrates as it sits.

Bring together in the bowl, transfer, form into a compact disk and chill a couple of hours or overnight.

Halve and peel large onions, trim the root leaving a little to hold the layers, and rotary cut into thin wedges.

Heat about a tablespoon of oil in the pan over medium high, melt in a tablespoon of butter, add the onions and kosher salt and stir once to coat.

Cook over high heat without stirring until well browned on the bottom, pushing them down as they wilt, to the edge of burning; turn once and lower the heat a little.

Add a little water and the sherry, scraping the bottom to dissolve the browning, then turn to medium low.

Add a couple of thyme sprigs, turn to low and cook about 25 to 30 minutes, adding a quarter cup of water at a time whenever it looks dry, so the onions stay a little saucy. Remove the stems and cool.

Wet the counter slightly and flour it so the flour sticks in a thin film; flour both sides of the dough and whack it to start it spreading.

Roll from the center out, pushing rather than pressing, flipping and flouring now and then, to slightly more than an eighth of an inch thick and about a 14-inch circle.

Roll the dough onto the pin and unroll it onto a parchment-lined sheet tray.

Crumble the goat cheese over, then spread the cooled caramelized onions leaving about a one-and-a-half-inch border.

Slice the potatoes paper thin on a mandolin, wearing a cut-resistant glove, so they cook in the short bake.

Toss the potato slices in a little olive oil, salt and pepper.

Preheat the oven to 400. Tuck the potatoes into the onions, scatter the Gruyere and a little pepper.

Fold the dough border over the filling, leaving the center open, using the paper to help, and press it down. Optionally chill before baking.

Bake on the middle or bottom rack at 400 for 40 to 45 minutes until bubbling and deep golden on the bottom.

Slide onto a platter on the parchment and slice; serve warm or at room temperature.