Add a spinach feta filling to the traditional rolled crescent rugelach shape and what do you get? These wonderful savory morsels. They're impressive enough for a party appetizer and quick enough for a weekend snack.
Preheat oven to 425 degrees F.Line two large baking sheets with parchment paper and set aside.
Take the frozen spinach out of the box or bag and let it soften slightly on a plate at room temperature. This should take just a few minutes while you prepare the other ingredients. If the spinach is not already chopped, roughly chop it.
In a medium-large pot or pan, melt the butter over medium heat. Add the chopped onion and a pinch of salt. Cook, stirring frequently, until the onion is soft and translucent, about 5-7 minutes. Add the minced garlic and a few turns of freshly ground pepper. Cook for an additional minute until the garlic becomes fragrant. Add the flour and mix it into the onion and garlic mixture, then stir in the heavy cream or milk. After mixing all that together, add the spinach and 1-2 more pinches of salt. Stir and continue to cook for a minute or two until the spinach is heated and the mixture is thoroughly combined. Add in the feta, lemon juice and a dash or two of hot sauce. Mix to combine and remove from heat. If necessary, adjust seasoning. Let the mixture cool down to room temperature.
Whether you're using store-bought or homemade dough, roll out one of the 2 pieces of dough onto a lightly floured surface into a circle about 1/4-inch thick and about 12/13-inches round. (In my experience, store-bought dough circles are usually a bit thicker and smaller than that. If your store-bought dough is already that size, then you can leave it "as is.")
Spread half of the spinach feta mixture evenly on top of the dough, leaving about 1/4-inch at the edge of the dough uncovered. (It looks like an uncooked spinach pizza.) Using a pizza cutter or knife, cut the circle in half, then quarters and then each quarter in half, so that you end up with 8 triangular wedges.
Gently roll up one wedge, beginning at the outer (widest part) and working toward the center. Don't press too hard or the filling will ooze out as you roll. Remove that rugelach and repeat the process until all of the wedges are rolled.
Place the formed rugelach on one of the parchment-lined baking sheets and repeat the process with the other piece of dough and the rest of the spinach feta mixture.
Using a pastry brush, lightly brush the egg wash (egg yolk mixed with a bit of water) on the tops of the rugelach. If the filling was not too salty, sprinkle a bit more salt on top.
Bake the rugelach for about 20 minutes, until golden brown. Let them cool on a wire rack for a few minutes. Serve while still warm, but easy to handle.
Be sure to let the filling cool down before you spread it on the dough. If you don't, the hot filling makes the dough too soft to roll up easily. (Molly doesn't mention this step in her directions - I'm not sure why.) For my first batch I didn't wait long enough and the still-hot filling made the dough too soft to roll up the wedges. I had to stop and refrigerate the dough with the filling on top - on a pizza tray - until it cooled down.
Molly pushes her filling all the way out to the edge of the circle. I prefer to keep mine just a bit inside the edge. The filling oozes out anyway and it's slightly neater if it's not right up against the edge.
When serving, warm the platter slightly so that it does not cool down the rugelach. I do this either by putting a bit of water on the platter and microwaving it, then draining and drying it or if the platter is oven-safe, I put warm it in the oven or toaster oven.
Leftover rugelach can be stored, covered in the refrigerator and reheated in the toaster oven.