Heat the oven to 450ºF.

• Scrub or peel the parsnips and trim off the ends; cut the parsnips lengthwise into quarters, then crosswise into 2-inch lengths.

On a sheet pan, toss the parsnips with the maple syrup; season with salt and pepper. Spread in an even layer; roast, stirring halfway through, until lightly browned and tender, 18 to 20 minutes.
While the parsnips roast, prepare the sauce.

• Cut the mushrooms into ¼-inch slices.
• Finely chop, press, or grate enough garlic to measure 1 teaspoon.
• Zest the lemon; cut the lemon into wedges for garnish.

In a large frying pan over medium-high heat, warm 1 to 2 teaspoons oil until hot but not smoking. Add the mushrooms, season with salt and pepper, and cook, stirring occasionally, until starting to brown, 2 to 3 minutes. Stir in the garlic and lemon zest; cook until fragrant, about 1 minute. Add the vegetable broth, bring to a vigorous simmer, and cook, stirring occasionally, until thickened, 4 to 6 minutes.
While the sauce simmers, prepare the chicken.

• Pat the chicken dry with a paper towel. Cut in half lengthwise to create 4 thin cutlets; season generously with salt and pepper.
• Crack the egg into a shallow bowl and season with salt and pepper. With a whisk or fork, lightly beat until just blended.
• In another shallow bowl, spread the almond meal.

Dip the chicken into the egg; let the excess drip off. Lightly press the chicken into the almond meal, coating all sides.
In a medium frying pan over medium heat, warm 2 tablespoons oil until hot but not smoking. Add the chicken; cook until golden brown and cooked through, 3 to 5 minutes per side. Transfer to a plate. While chicken cooks, prepare the parsley.

• Strip the parsley leaves from the stems; coarsely chop the leaves.

Remove the mushroom sauce from the heat. Stir in the parsley and butter, if using. Season to taste with salt and pepper.

Transfer the chicken to individual plates; top with the mushroom sauce. Serve with the parsnips and lemon wedges.