Prep the apples. Peel, core, and slice the apples into 1/2-inch thick wedges. Thinner slices cook faster and softer; thicker slices hold shape better.

Grease the slow cooker. Lightly butter the insert or use a quick spritz of cooking spray to keep the apples from sticking.

Mix the flavor base. In a small bowl, stir together cinnamon, brown sugar (or maple/honey), a pinch of salt, and optional spices. If using cornstarch for a thicker sauce, whisk it into this mixture.

Layer and toss. Add apples to the slow cooker. Drizzle with lemon juice and vanilla, then sprinkle the spice mixture over the top. Toss gently to coat.

Add butter. Dot the top with small pieces of butter for a glossy finish and deeper flavor.

Cook low and slow. Cover and cook on Low for 3–4 hours, or on High for 1.5–2 hours. Stir once halfway through to ensure even cooking.

Check for doneness. The apples should be tender and glossy but not falling apart. If the sauce looks thin, remove the lid and cook on High for 10–15 minutes to thicken slightly.

Taste and adjust. Add a touch more cinnamon, sugar, or lemon if needed. Serve warm or let cool before storing.