To make the cheese filling, get a mixing bowl and add garlic powder, parmesan cheese, Italian seasoning, and cream cheese. Mix everything together until it's well combined.
Now, just leave it aside for the time being.
First, heat up your oven to 400 degrees. Then, get a baking sheet and cover it with a lining.
Take the mushrooms and give them a good clean. In this recipe is mentioned "How To Clean Mushrooms" Once done, use a paper towel to gently drain them.
Next, drizzle some olive oil onto the mushrooms. Add a coating of garlic powder on top, and sprinkle a pinch of salt.
Take the cream cheese filling you made earlier and use it to stuff the empty centers of the mushrooms.
Now, put the mushrooms on the baking sheet you prepared earlier.
Place the baking sheet with the mushrooms in the preheated oven and let them roast for about 10 - 15 minutes.
Take another bowl and add flour, worcestershire sauce, white wine, half-and-half, dry mustard, pepper, and mayonnaise to it.
Mix all of the ingredients in the bowl together until they're well combined.
Then, add the white cheddar cheese to the mixture. Once it's mixed in, transfer everything to a pot.
Place the pot with the mixture on the stove over medium heat. Let it simmer while stirring occasionally until the mixture turns creamy.
Once the white cheddar sauce is ready, pour it over the mushrooms on the baking sheet. Place the mushrooms on top of the sauce.
Your delicious stuffed mushrooms with white cheddar sauce are now ready to serve. Enjoy your tasty appetizer!