Heat oil in large, non-stick skillet. Saute onions, leek, garlic, and mushrooms until tender. Remove from pan, and place in large mixing bowl.
Wash spinach thoroughly. Return skillet to heat and place wet spinach in pan. Cover and steam, stirring occasionally until limp. Cool, chop, and squeeze as much moisture out with your hands as you can. Add to vegetables in mixing bowl. (If using frozen spinach, skip this step and add drained frozen spinach to bowl) Let cool.
Add dill weed, cheeses, and eggs. Stir to combine.
Spread phyllo sheets on cutting surface. Unroll, and cut in half lengthwise. Cover with damp cloth or plastic wrap. Combine melted butter and olive oil.
Remove one half-sheet. Fold in half lengthwise, and brush very lightly with melted butter mixture. You are not aiming to coat the surface - only to provide enough butter to stick the layers together as you roll it.
Place a mounded tablespoon of spinach mixture on one end of the phyllo strip. Fold the corner up diagonally, making a triangle with the spinach inside. Continue to fold/roll from side to side, enclosing the spinach until the strip is used. Brush with butter and place on baking sheet.
Continue, filling one strip at a time, and keeping the other's covered.
Bake at 350F for 35-45 minutes until golden. (or freeze before baking fur future use).