Sausage Stuffed Mushrooms

2 tbsp. olive oil, plus more for pan	1/4 c. chopped fresh flat-leaf parsley
1 lb. button mushrooms or cremini (about 32 mushrooms)	1 tsp. grated lemon zest, plus 2 tsp juice
1 shallot, chopped	1 tsp. fresh thyme leaves, chopped
2 cloves garlic, chopped	1/4 cup panko breadcrumbs
4 oz. (about 1 link) sweet sausage, casing removed	1/4 cup grated Parmesan

Directions:

Preheat oven to 350ºF. Lightly grease a large, rimmed baking sheet.
Remove stems from mushrooms and chop.
Place mushroom caps, stem sides up, on prepared baking sheet.
Heat oil in a large skillet over medium heat.
Add shallot and garlic. Season with salt and pepper.
Cook, stirring occasionally, until tender, 3 to 4 minutes.
Add chopped mushroom stems and season with salt and pepper.
Cook, stirring, until starting to brown, 7 to 9 minutes.
Add sausage and cook, breaking it into small pieces with a wooden spoon, until browned and cooked through, 5 to 6 minutes; transfer to a bowl.
Add parsley, lemon zest and juice, thyme, panko, and Parmesan, and stir to combine.
Fill mushroom caps with filling.
Bake until mushrooms are tender, 28 to 30 minutes. Serve immediately.