To prepare the dough:

1. Pulse the flour and salt in a food processor to combine. Add the butter, cream cheese, and sour cream and pulse, pulse, pulse the mixture until a dough comes together. Don’t overwork it. Pat the dough out on a lightly floured surface into a flat round disk. Wrap in plastic wrap and refrigerate until well-set, a couple of hours or even overnight.
2. When ready to assemble, roll your disk out onto a lightly floured surface into a round circle, about 1/8-1/4” thick. Make sure your dough isn’t sticking to your surface before you add your filling! For the savory rugelach, spread the fig spread all over the entirety of the dough circle and then sprinkle on the blue cheese and walnuts. For the sweet rugelach, use a pastry brush to paint on the butter and then evenly sprinkle on the white chocolate and almonds. Use a sharp chef’s knife or a pizza cutter to cut the circle into 16 equal-sized wedges. The fat end of each wedge will be about 1” thick. Starting with the wide end, tightly roll up the rugelach until they’re little spiral dough pieces and place each one on a small parchment lined baking sheet, about 2 inches apart. Be sure your wedges are tightly rolled so that the rugelach don’t come unrolled in the oven. Place the pan in the freezer for 20 minutes or the fridge for an hour to chill.
3. When ready to bake, preheat the oven to 350 degrees. Remove from the fridge and brush the whisked egg all over each pastry. Sprinkle sugar on the white chocolate pastries. Bake in the preheated oven about 30 minutes, or until the pastries are golden brown. Remove from oven and allow to cool some before serving.