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Apple Crumble Cake Bars

Prep Time 45 minutes
Cook Time 55 minutes
Total Time 1 hour 40 minutes
Servings: 9 squares
Course: Dessert
Cuisine: American, Fall Baking

Ingredients
  

Cookie Base
  • 170 g ¾ cup unsalted butter, softened room temperature
  • 150 g ¾ cup light brown sugar, packed
  • 50 g ¼ cup granulated sugar
  • 1 large egg room temperature
  • 2 tsp pure vanilla extract
  • 210 g 1¾ cups all-purpose flour
  • ½ tsp baking powder
  • ¼ tsp baking soda
  • ¼ tsp fine salt
  • ½ tsp ground cinnamon
Apple Filling
  • 2 medium apples ≈250 g, peeled and diced small (mix of Honeycrisp and Granny Smith)
  • 50 g ¼ cup apple butter
  • 30 g 2 Tbsp unsalted butter
  • 50 g ¼ cup light brown sugar, packed
  • ½ tsp ground cinnamon
  • 15 g 1 Tbsp apple cider or water
  • 1 tsp cornstarch
  • Pinch fine salt
Oat Streusel Topping
  • 80 g ⅔ cup all-purpose flour
  • 60 g ¾ cup old-fashioned oats
  • 100 g ½ cup light brown sugar, packed
  • ¼ tsp fine salt
  • ½ tsp ground cinnamon
  • 85 g 6 Tbsp unsalted butter, cold and cubed
Toffee or Caramel Drizzle
  • 100 g ½ cup light brown sugar
  • 60 g ¼ cup unsalted butter
  • 80 ml ⅓ cup heavy cream
  • Pinch fine salt
  • Or use store-bought toffee or caramel sauce, such as Torani Toffee Nut or Cartwright & Butler

Equipment

  • 8x8-inch baking pan – light metal bakes most evenly; glass may need ~5 extra minutes
  • Parchment paper
  • Medium saucepan
  • Mixing bowls (2-3)
  • Electric mixer or whisk – helps cream butter and sugar smoothly for cake base
  • Rubber spatula
  • Wooden spoon
  • Cooling rack
  • Measuring cups and spoons
  • Kitchen scale – for precise, bakery-style results every time

Method
 

Make the Apple Filling
  1. In a saucepan over medium heat, melt 30 g (2 Tbsp) unsalted butter.
  2. Add 50 g (¼ cup) light brown sugar, ½ tsp cinnamon, and a pinch of salt; stir and let bubble for 1 minute.
  3. Add 2 medium apples (≈250 g, diced) and cook 3–4 minutes until they just start to soften.
  4. Stir in 50 g (¼ cup) apple butter until glossy.
  5. In a small bowl, whisk 1 tsp cornstarch into 15 g (1 Tbsp) apple cider or water, then pour into the pan and stir until the mixture thickens and turns syrupy.
  6. Spread filling onto a plate and cool completely before layering.
Make the Streusel
  1. In a bowl, mix 80 g (⅔ cup) flour, 60 g (¾ cup) oats, 100 g (½ cup) brown sugar, ¼ tsp salt, and ½ tsp cinnamon.
  2. Cut in 85 g (6 Tbsp) cold butter using a fork or fingertips until crumbly.
  3. Refrigerate until ready to use.
Make the Cookie Base
  1. Preheat oven to 340°F (170°C). Line an 8×8-inch pan with parchment paper and leave overhang for easy removal.
  2. Cream 170 g (¾ cup) softened butter with 150 g (¾ cup) brown sugar and 50 g (¼ cup) granulated sugar until smooth and fluffy.
  3. Whisk in 1 large egg and 2 tsp vanilla extract until glossy.
  4. Add 210 g (1¾ cups) flour, ½ tsp baking powder, ¼ tsp baking soda, ¼ tsp salt, and ½ tsp cinnamon. Mix until just combined.
  5. Spread evenly into pan, then tap the pan firmly on the counter 2–3 times to burst air pockets and level the batter.
Assemble and Bake
  1. Spread the completely cooled apple filling evenly over the cookie base.
  2. Sprinkle chilled streusel topping evenly on top, pressing it lightly into the surface.
  3. Bake for 50–55 minutes at 340°F (170°C), until golden brown on top and edges are set.
  4. Cool completely in the pan before cutting.
Make the Drizzle (Optional)
  1. If using store-bought toffee or caramel, drizzle directly over cooled bars before serving.
  2. To make homemade sauce: In a small saucepan, melt 60 g (¼ cup) butter and 100 g (½ cup) brown sugar over medium heat; whisk 2–3 minutes until bubbling.
  3. Add 80 ml (⅓ cup) heavy cream and a pinch of salt; simmer 2 minutes more until glossy and slightly thickened.
  4. Cool slightly, then drizzle over the bars.
Tips & Tricks
  1. Lower oven temperature (340°F) helps the center rise evenly without the edges over-browning.
  2. Tap the pan firmly on the counter before baking to release air bubbles and prevent thicker edges.
  3. Cool the apple filling completely before layering to avoid soggy bars.
  4. Texture tip: The apples should still have a little bite after cooking—soft but not mushy.
  5. Use a light-colored metal pan for even baking; dark pans brown faster, and glass pans may need 5 extra minutes.
  6. Slice after cooling: Let the bars set fully in the pan before cutting for clean edges and neat layers.
  7. Toffee drizzle shortcut: Store-bought sauces like Torani Toffee Nut or Cartwright & Butler work perfectly if you don’t want to make your own.

Notes

Storage & Make-Ahead
• At room temperature: Keeps up to 2 days, covered loosely with foil or in an airtight container.

• In the fridge: Lasts up to 5 days. Rewarm slices slightly before serving to soften the crumble and bring back that fresh-baked texture.

• In the freezer: Wrap bars individually and freeze for up to 2 months. Thaw overnight in the refrigerator and drizzle just before serving.

• Make-ahead option: Bake and cool fully, then store (without drizzle) in an airtight container. Add the toffee or caramel drizzle right before serving for the best texture and flavor.

• Serving tip: These bars are even better on day two once the flavors meld — cozy, buttery, and perfectly balanced.