To start, the spinach needs to be as dry as possible. Layer 4 paper towels, place spinach in the center and squeeze out as much liquid as you can. Repeat with artichoke hearts. Keep doing this until it is very dry. You can even put it in the refrigerator uncovered for an hour or so to dry.
Stir together mayonnaise, cheeses, onion powder, garlic powder, white pepper, artichoke hearts and spinach. Blend well.
Roll out one sheet of puff pastry. Brush extra virgin olive oil over the puff pastry sheet. Spread half of the mixture onto the puff pastry sheet leaving a one inch margin on each side.
Roll up sheet tightly. Wrap in plastic wrap.
Repeat with second puff pastry sheet.
Place in freezer for 20-30 minutes. Just long enough for the ingredients to solidify, but not so hard you can't cut through it.
Preheat oven to 400 degrees. Remove rolls from the freezer and cut into 1 inch thick slices or 12 per roll.
Line a jelly roll pan with parchment paper.
Bake for 15 minutes or until puffy and lightly browned. Allow to stand for 3-5 minutes before serving.
If you've tried this recipe, make sure to come back and let us know how it went!