Preheat oven to 400 degrees F. Line a baking sheet with aluminum foil and coat with cooking spray.

Combine the olives, sun-dried tomatoes, and oil in a food processor and pulse until the mixture forms a rough and kinda chunky paste.

Lightly flour a work surface and rolling pin. Roll dough into a 14x10-inch rectangle. Spread with olive mixture, leaving a 1-inch border around the dough edges on all sides. Top mixture with overlapping slices of cheese; add the spinach in an even layer.

Finally add the mushroom strips in a single layer, long sides parallel to the long sides of the dough rectangle.

Fold 1 inch of dough over the filling on the short sides of the rectangle. Fold the long ends over the filling, pinching the dough together at the corners. Roll the dough, starting at one of the long ends, as tightly as possible. Before the roll is done, brush the border lightly with egg and pinch the seam to seal.

Carefully transfer the roll, seam side down, to the prepared baking sheet. Brush lightly with the egg. Bake for 25 to 30 minutes, until the bread is golden.

Loosen the bottom of stromboli from the foil with a spatula. Transfer to a cutting board, let cool, and cut slices.