Prepare your apples: Peel, core, and slice the apples into roughly 1/4-inch thick pieces. Aim for consistent thickness so they cook evenly.
Melt the butter: In a large skillet over medium heat, melt the unsalted butter until it's foamy.
Add apples and spices: Add the sliced apples to the skillet. Sprinkle the brown sugar, cinnamon, nutmeg, and a pinch of salt over the apples. If using, drizzle the lemon juice over the top.
Cook until tender: Stir gently to coat the apples evenly. Cook for about 10-15 minutes, stirring occasionally, until the apples are tender but not mushy, and the sauce has thickened into a syrupy glaze. Adjust heat as needed to prevent burning.
Serve warm: Once cooked to your desired tenderness, remove from heat and serve immediately.