Heat 1 tablespoon of butter in a large skillet over medium heat.
Add the sliced mushrooms and leave them alone for 3-4 minutes.
Flip and continue to cook until golden brown, about 2-3 minutes.
Add the minced shallot then cook, stirring often, for 2 minutes.
Add the minced garlic and cook, stirring constantly, for 1 minute.
Season with sea salt and freshly cracked pepper, to taste. Pour the mushrooms into a bowl; set them aside.
In a bowl, season the flour with garlic powder, and some sea salt & freshly cracked pepper, to taste; mix until well combined.
Whisk eggs until well combined, in a separate bowl.
Cut the thin portion of the bottom couple inches of the chicken breast off. Cut each remaining portion of the chicken breast in half then cut each of those pieces in half lengthwise. Place some saran wrap over the top of the chicken on the cutting board, and pound with a mallet until they are about a ¼-½ inch thick.
Heat two tablespoons of olive oil in a large skillet over medium-high heat.
Dip the chicken lightly in the seasoned flour, next dip into the whisked egg, and lastly dip back into the flour before placing into the hot oil in the skillet; repeat with remaining chicken, cooking in batches if needed.
Cook the chicken undisturbed until golden brown, about 4-5 minutes then flip over and continue to cook until golden brown and cooked through, about 3-4 minutes.
Remove from the skillet and place on a paper towel lined plate. Cover loosely with a tin foil tent.
Add a tablespoon of butter to the pan then whisk in the flour until well combined.
Add the wine and whisk until thickened, about 1 minute.
Slowly add the chicken stock and lemon juice while whisking; simmer for 2-3 minutes.
Add the mushrooms and their liquids to the sauce; mix well.
Whisk in the tablespoon of butter then taste and season with sea salt and freshly cracked pepper, to taste, add more lemon if needed.
Place the chicken on a serving platter then drizzle with mushroom sauce and sprinkle the top with fresh parsley.