Mushroom-Thyme Pot Pies

Heat oil and 2 Tbsp. butter in a medium saucepan over medium.

Cook onion, stirring occasionally, until very soft, 10–12 minutes.

Add tomato paste and cook, stirring often, until color darkens and paste completely coats onion, about 1 minute.

Add button mushrooms and cook, stirring occasionally, until softened and any liquid has evaporated, 12–15 minutes.

Add sherry and cook until almost completely evaporated, about 5 minutes.

Add broth and porcini mushrooms.

Bring to a simmer and cook until reduced by half (about 2 1/2 cups), about 1 hour.

Strain mushroom broth through a fine-mesh sieve into a medium bowl, pressing down on solids; discard solids.

Heat remaining 3 Tbsp. butter in a large saucepan over medium.

Whisk in flour and cook, whisking often, until flour begins to smell nutty, about 4 minutes.

Whisking vigorously to prevent lumps, add mushroom broth and increase heat to medium-high.

Bring to a simmer and cook 1 minute.

Remove from heat.

Place a rack in middle of oven; preheat to 425°F.

Combine fennel, onions, 1 Tbsp. butter, and 1 cup water in a small saucepan; season with kosher salt and pepper.

Bring to a boil over medium-high, cover, and reduce heat.

Simmer until fennel and onions are crisp-tender, 5–8 minutes.

Uncover; cook until liquid evaporates, 15–18 minutes.

Heat remaining 2 Tbsp. butter in a large skillet over medium.

Cook thyme sprigs and mushrooms, tossing occasionally, until mushrooms are browned and tender, 6–8 minutes.

Let cool; pluck out thyme.

Divide fennel mixture and mushrooms among ramekins.

Spoon gravy over top.

Divide dough in half.

Working with one at a time, roll out to 1/4" thick.

Cut out 2 rounds about 1/2" wider than the diameter of ramekins.

Gather up scraps, reroll, and cut out 2 more rounds (for 8 total).

Whisk egg, a pinch of kosher salt, and 1 tsp. water in a small bowl.

Brush dough with egg wash; place over ramekins, brushed side down.

Press firmly around sides to adhere.

Brush tops of dough with egg wash; sprinkle with thyme leaves and sea salt.

Set pot pies on a rimmed baking sheet and bake until crusts are golden brown and domed, 25–35 minutes.

Dough can be made 3 days ahead.

Keep chilled.

Gravy can be made 3 days ahead.

Let cool; cover and chill.

Pot pies (without brushing outside of pastry and topping) can be assembled 1 day ahead.

Cover pot pies and extra egg wash separately and chill.