Combine the flour and salt. Crumble the room temperature butter and add the rest of the ingredients. Knead the ingredients into a dough. You should get a very soft and sticky dough. Place it on a floured surface and knead it for one more minute. Form a log shape and cut off 1/3rd of the dough. Flatten each one and form them to a rectangle shape and wrap with a parchment paper. Put the dough into the fridge for 45 minutes.
After resting roll out the larger piece of dough on a floured parchment paper to a 9x13-inch rectangle and put it into the baking pan. Spread the jam on the dough evenly.
Now beat the egg whites with sugar until stiff peaks form. Add the breadcrumbs, the egg yolks, lemon zest, cinnamon and walnuts. Spread the meringue on the dough and add the sour cherries. Form rope shapes from the smaller dough and make a lattice pattern on top of the meringue.
Bake it in a preheated 350 F oven for 40-45 minutes.
Let it cool down completely before slicing.

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