Preheat oven to 350 degrees

In medium bowl, combine ground beef, Worcestershire sauce, mustard and garlic. Add Salt and Pepper and mix until fully combined.

In large bowl, toss mushroom caps with oil and season with salt.

Line a baking sheet with parchment paper and place mushroom caps on it.

Taking small amounts of the beed mixture and stuff into the wells of the mushroom caps and bake for 20 minutes.

Remove from the oven and place a couple of slices of cheddar on each cap. Return to the oven for 10 more minutes.

When finished cooking top with tomato and pickle and serve.