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two creamy lemon crumble bars on a green plate

Oatmeal Lemon Crumble Bars

  • Author: Sally
  • Prep Time: 15 minutes
  • Cook Time: 38 minutes
  • Total Time: 2 hours (includes cooling)
  • Yield: 16 bars
  • Category: Bars
  • Method: Baking
  • Cuisine: American


These easy lemon crumble bars feature an oatmeal crust, thick and creamy lemon filling, and more oatmeal crumble on top.


Crust & Topping

  • 7 Tablespoons (99g) unsalted butter, softened to room temperature (yes, 7 Tbsp!)
  • 3/4 cup (150g) packed light or dark brown sugar
  • 1 teaspoon pure vanilla extract
  • 1 cup (125g) all-purpose flour (spooned & leveled)
  • 1 teaspoon baking powder
  • 1/4 teaspoon salt
  • 1 cup (85g) old-fashioned whole oats or quick oats (not instant)

Lemon Filling

  • 1 (14-ounce weight) can full-fat sweetened condensed milk
  • 6 Tablespoons (90ml) lemon juice (about 2 lemons)
  • 1 Tablespoon lemon zest (about 1 lemon)


  1. Preheat oven to 350°F (177°C). Line an 8-inch square pan with parchment paper.
  2. For the crust/topping: Using a handheld or stand mixer fitted with a paddle attachment, beat the butter and brown sugar together on medium-high speed until combined, about 1 minute. Scrape down the sides and up the bottom of the bowl with a rubber spatula and then add the vanilla extract. Beat on medium-high speed until combined, about 30 seconds. Add the flour, baking powder, salt, and oats. Beat on medium speed until combined. Scrape down the sides and up the bottom of the bowl and beat again as needed to combine. Mixture will appear dry and be crumbly. You will have between 3–3.5 cups of crust/crumble mixture.
  3. Lightly press a little more than half of crumble mixture into bottom of prepared baking pan. (You want a little more mixture for the crust than for the topping.) Bake for 12 minutes.
  4. Meanwhile, make the lemon filling: Whisk sweetened condensed milk, lemon juice, and lemon zest together. Mixture will be thick.
  5. Pour and spread filling over pre-baked crust (while crust is hot). Sprinkle the remaining crumble mixture on top.
  6. Return bars to the oven and bake for 22–25 minutes or until edges are very lightly browned and appear set. Avoid over-baking. Remove from the oven and place the pan on a wire rack. Cool bars completely.
  7. Lift the bars out using the parchment paper overhang on the sides. Cut into squares.
  8. Cover leftover bars and store at room temperature for up to 2 days or in the refrigerator for up to 1 week.


  1. Freezing Instructions: Freeze cut bars in single layers between sheets of parchment paper in a freezer-friendly container for up to 3 months. Thaw overnight in the refrigerator and bring to room temperature before enjoying.
  2. Special Tools (affiliate links): 8-inch Square Baking Pan | Parchment Paper | Electric Mixer (Handheld or Stand) | Glass Mixing Bowl | Whisk | Zester | Juicer
  3. Recipe updated in 2022: Older version used 1 pouch (1 lb 1.5 oz) Betty Crocker oatmeal cookie mix for the crust & topping. Cut 1/2 cup (115g) cold unsalted butter into cookie mix with a pastry cutter and then stir in 1 egg. This mixture replaced the homemade crust & topping recipe above. Continue with step 3 above.
  4. Sweetened Condensed Milk: Make sure you are using sweetened condensed milk, not evaporated milk. There are no successful replacements for sweetened condensed milk in this particular recipe—it’s really the key ingredient. (Sometimes half-and-half or heavy cream works as a substitution, but then you’ll have to test with varying amounts of sugar since both are unsweetened.) Use one 14-ounce can full-fat sweetened condensed milk. Do not use fat-free because the filling will not set. Keep in mind that 14 ounces is the listed weight on the can. 1 standard 14-ounce can is a little over 1 liquid cup.
  5. Can I Double This Recipe? Yes. Double each ingredient and bake in a 9×13 inch pan. Increase crust pre-bake time to 18 minutes. Increase the bake time after adding the filling & crumble topping to 35 minutes, or until edges are lightly browned and appear set.

Keywords: oatmeal lemon crumble bars