Overnight Slow Cooker Apple Cinnamon Steel-Cut Oats

Why You’ll Love This Recipe

• Hands-off overnight cooking means breakfast is ready when you wake up.
• Steel-cut oats keep a creamy-yet-toothsome texture—never gluey.
• Apple, cinnamon, and raisins add cozy, natural sweetness.
• Leftovers reheat beautifully for fast weekday breakfasts.

Grocery List

• Produce: 2 medium apples
• Dairy: Whole milk, plain Greek yogurt
• Pantry: Steel-cut oats, raisins, ground cinnamon, vanilla extract, light brown sugar, kosher salt, walnuts

Full Ingredients

For the Overnight Oats

• 1 1/2 cups steel-cut oats (not quick-cooking)
• 2 medium apples, cored and diced 1/2-inch (about 2 1/2 cups; Honeycrisp, Fuji, or Granny Smith work well)
• 3/4 cup raisins
• 1 1/2 teaspoons ground cinnamon
• 1 teaspoon pure vanilla extract
• 1/3 cup packed light brown sugar
• 1/2 teaspoon kosher salt (or 1/4 teaspoon fine sea salt)
• 4 cups water
• 2 cups whole milk (or 2% for lighter; see Variations for dairy-free)

For Serving

• 1/2 cup chopped walnuts, toasted
• 1 cup plain Greek yogurt (2% or whole; swirl into each bowl)
• Optional: extra ground cinnamon or a drizzle of honey

Step-by-Step Instructions

Step 1: Toast the walnuts

Preheat the oven to 350°F. Spread walnuts on a small baking sheet and toast for 6 minutes, until fragrant and lightly darkened. Cool, then chop. Alternatively, toast in a dry skillet over medium heat for 3–4 minutes, stirring often.

Step 2: Prep the slow cooker and apples

Grease a 4- to 6-quart slow cooker insert with a little butter or nonstick spray to minimize sticking. Core and dice the apples into 1/2-inch pieces. You do not need to peel them unless you prefer a softer texture.

Step 3: Load the slow cooker

Add steel-cut oats, diced apples, raisins, cinnamon, vanilla, brown sugar, and salt to the prepared slow cooker. Pour in the water and milk. Stir well, making sure the cinnamon and sugar are evenly dispersed and no dry pockets of oats remain along the edges.

Step 4: Cook low and slow overnight

Cover and cook on Low for 8 hours. On most slow cookers, Low corresponds to roughly 190–200°F; if your unit runs hot, reduce cook time to 7 1/2 hours. Do not stir during cooking.

Step 5: Stir to creamy perfection

In the morning, uncover and stir vigorously for 30–60 seconds. The oats will turn creamy as the starch emulsifies. If the porridge is thicker than you like, stir in warm milk or water 1/4 cup at a time until it reaches your preferred consistency. Taste and adjust with a pinch of salt or a teaspoon of brown sugar if needed.

Step 6: Finish and serve

Ladle into warm bowls. Add a generous swirl of Greek yogurt (about 2 tablespoons per serving) and sprinkle with toasted walnuts (about 1 tablespoon per serving). Dust with a pinch of cinnamon or drizzle with honey if you like.

Step 7: Store the leftovers

Cool leftovers to room temperature, then portion into airtight containers. Refrigerate for up to 5 days or freeze for up to 3 months. Reheat gently with a splash of milk or water on the stovetop or in the microwave, stirring until creamy again.

Pro Tips

• Use true steel-cut oats, not quick-cooking or rolled oats, for the best texture.
• Greasing the crock helps prevent sticking; for ultra-creamy oats with zero scorching, place a smaller heatproof bowl of oats inside the slow cooker and pour hot water around it to create a water bath.
• Apple choice matters: tart Granny Smith stays firmer; Honeycrisp or Fuji become soft and sweet.
• Stir well after cooking—this turns separate grains into a luxuriously creamy porridge.
• Adjust thickness with warm liquid at serving time; oats continue to thicken as they stand.

Variations

• Dairy-Free: Use 6 cups unsweetened almond milk or 4 cups water + 2 cups canned light coconut milk; serve with non-dairy yogurt.
• Maple-Pecan: Swap brown sugar for 1/3 cup pure maple syrup and use toasted pecans instead of walnuts.
• Carrot Cake Oats: Add 1 cup finely grated carrot, 1/4 teaspoon ground nutmeg, and 1/4 cup chopped pineapple; finish with raisins and walnuts.

Storage & Make-Ahead

Refrigerate cooked oats in airtight containers for up to 5 days or freeze for up to 3 months. Reheat with 2–4 tablespoons milk or water per serving on the stovetop over low heat or in the microwave (1–2 minutes), stirring midway. To prep ahead, combine dry ingredients in a jar and keep at room temperature; dice apples the night before and refrigerate.

Nutrition (per serving)

Approximate values with toppings (1 tablespoon walnuts and 2 tablespoons Greek yogurt): 410 calories; 66 g carbohydrates; 12 g protein; 11 g fat; 3.5 g saturated fat; 6 g fiber; 29 g total sugars; 200 mg sodium. Estimates will vary based on milk and yogurt choices.