Make Filling

1. Defrost, drain and dry the chopped spinach completely with paper towels and place in a food processor
2. Give the sun-dried tomatoes a rough chop with your knife, and add these to food processor along with some freshly-ground black pepper
3. Pulse together with the oil. Add enough oil to get the filling to a smooth and paste-like consistency. Set mixture aside while you roll out the puff pastry

Roll Out Pastry & Add Filling

1. Flour work surface, both sides of the puff pastry, and rolling pin
2. Roll out the puff pastry sheet to half of its original thickness
3. Spread the spinach and tomato mixture evenly across the pastry, making sure to leave 1" of space around the perimeter
4. Add the crumbled feta on top, sprinkling evenly
5. Brush the top and side edges of the puff pastry with the egg wash. Roll up the pastry, forming a loaf.  Place on a cutting board or plate and refrigerate 10 minutes until firm

Slice & Bake
(Great Do-Ahead Idea:  At this point, you could slice the pinwheels, place them on a parchment-lined baking sheet and freeze them.  Once frozen, remove from baking sheet and place in freezer bag or freezer-safe container.  When ready to bake, spread out on parchment-lined baking sheet, let come to room temperature, then bake as per the following instructions.)

1. Preheat oven to 400º
2. Slice the loaf in ½” thick slices, forming pinwheels (you may need to discard the first and last pinwheels, as they most likely contain no filling)
3. Place pinwheels on a parchment-lined baking sheet and bake 15-20 minutes until puffed and golden brown