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  1. To make the pastry: In a large bowl, whisk together the flour, sugar, and salt. Work in the cream cheese until it's the size of small peas. Work in the butter, leaving some pieces the size of your thumbnail. Sprinkle the ice water over the dry mixture 2 tablespoons at a time. Stir with a fork, adding additional water 1 tablespoon at a time, until the mixture feels damp to the touch.

  2. Turn the mixture out onto a piece of parchment and fold it over on itself until it holds together. Sprinkle or spray any dry sections with more water as needed. Once the dough is cohesive, pat it into a 9" disk, wrap, and chill for 30 minutes.

  3. After chilling, roll the dough out to a 16" circle, trimming the outside of the circle to neaten up the edge. Place on a parchment-lined or lightly greased baking sheet. Preheat the oven to 425°F.

  4. To make the filling: Sprinkle the diced ginger over the dough, leaving a 3" border around the outer edges uncovered. In a small bowl, whisk together the sugar, Instant ClearJel (or flour), allspice, and salt. Sprinkle half of this mixture over the ginger, again leaving a 3" border clear around the edge.

  5. Pit and slice the plums and arrange the slices over the dough, once again leaving the edges clear. Sprinkle the remaining sugar mixture over the plums.

  6. Fold the outside edges of the dough up and over the filling, pleating as necessary as you go around the circle.

  7. Bake the galette for 30 to 35 minutes, until the plums are bubbling and the pastry is golden brown. Remove it from the oven and cool on a rack before slicing and serving.

  8. Store any leftovers, lightly wrapped in plastic, at room temperature for a couple of days; freeze for longer storage.