Heat oil in a pan and add chopped onion, spring onion, celery and minced garlic.
When onion becomes soft (no need to brown it), add chopped mushroom.
When mushroom is cooked and water is dried, add chopped spinach leaves.
Add salt and pepper to this and remove from fire.
In a saucepan, melt butter.
Add plain flour to this and roast until the raw smell goes 3-5 minutes. Make sure the flour doesn't brown.
Add milk gradually and keep stirring.
Add cheese and cook until it melts.
When it reaches a thick sauce consistency, add it to the mushroom and spinach mixture.
Mix all the ingredients (plain four, eggs, water and salt) well in a large bowl. Using a balloon whisk or blend them in a blender until everything is blended without lumps.
Heat a small frying pan onto medium heat; pour ½ a ladle of batter to form circles of 5” diameter. Just cook the pancake on one side ONLY and remove. (The pancake will be cooked on both sides this way). Place them on a plate rubbed with oil.
Keep the filling on the uncooked side of the pancake. Place the filling as a line on the side facing you. Make sure to leave some gap around the edges .Fold the left and right sides of the wrapper/pancake over the mixture. Gently pull away the edge of pancake facing you and roll over the filling.
Continue to fold the roll. Seal the edges using the flour paste mentioned in the notes. When you fill one spring roll, you can start making the next one.
Dip the roll in lightly beaten egg whites and then roll it in breadcrumbs until fully coated. Heat a frying pan filled halfway with oil. Fry these rolls in the oil until golden and crisp.
Serve hot with tomato ketchup or sweet chilli sauce.