Sour Cream Raisin Squares with Oat Crust
Sour cream raisin squares are a classic bar cookie featuring a buttery oat crumb base topped with a tangy, custard-like filling studded with plump raisins. What makes this version special is the dual-bake method: the base bakes first to set, then the creamy filling is added before a final bake that sets the topping crumbs to golden. The filling relies on egg yolks and sour cream for richness and tang, balanced by sweet raisins and sugar. The texture contrast between the crisp oat crust, velvety filling, and crumbly top layer creates depth. This is ideal for home bakers seeking a make-ahead dessert for potlucks, church socials, or weeknight treats. Serve these at room temperature for afternoon coffee, as a lunchbox treat, or alongside tea. The oat base distinguishes it from cream cheese or custard versions while the sour cream filling adds complexity beyond standard raisin bar recipes.
Ingredients
- 1 cup butter, softened
- 1 cup brown sugar, packed
- 2 cups all-purpose flourwhole wheat flour1:1nutrition boost
denser crumb
- 2 cups quick-cooking oats
- 1 teaspoon baking powder
- 1 teaspoon baking soda
- ⅛ teaspoon salt
- 4 egg yolks
- 2 cups sour cream
- 1 ½ cups raisins
- 1 cup sugar
- 1 tablespoon cornstarch
Instructions
- 1
Cream butter and brown sugar until light and fluffy.
- 2
Combine flour, oats, baking powder, baking soda, and salt; gradually add to creamed mixture until crumbly.
- 3
Set aside 2 cups of crumb mixture; press remaining crumbs into prepared pan.
- 4
Bake for 15 minutes at 350 degrees.
- 5
Cool completely.
- 6
In a small saucepan, combine egg yolks, sour cream, raisins, sugar, and cornstarch.
- 7
Bring to a boil; cook and stir for 5 to 8 minutes until thickened.
- 8
Pour filling over crust.
- 9
Sprinkle reserved crumbs over filling.
- 10
Bake for 15 minutes longer until top is set.
Tips
Press the base crust firmly and evenly into the pan using the bottom of a measuring cup or your hands to ensure even baking and consistent texture throughout.
Watch the filling closely as it cooks; it thickens rapidly once it reaches a boil. Stirring constantly prevents lumps and ensures a smooth, creamy layer.
Cool the base completely before adding filling to prevent the filling from soaking into warm crumbs and creating a soggy layer.
Good to Know
Cover and refrigerate up to 5 days. Store in an airtight container with parchment between layers to prevent sticking.
Prepare and bake fully one day ahead. Store covered at room temperature or refrigerated. Do not freeze filled squares; the filling becomes grainy when thawed.
Serve at room temperature. Cut into squares; pairs well with coffee, tea, or milk.
Common Mistakes
Do not skip cooling the base to avoid a soggy filling layer that won't set properly.
Do not underestimate the filling cook time; if underdone, it will remain thin and runny after baking.
Do not overbake the top layer; 15 minutes is enough to set the crumbs without drying the filling.
Substitutions
Dairy-Free Swaps
General Alternatives
FAQ
Can I make these without egg yolks?
Eggs provide structure and richness to the filling. Omitting them will result in a thin, custard-like layer that may not set properly. No reliable egg-free substitute works identically in this specific recipe.
What if I don't have quick-cooking oats?
Old-fashioned rolled oats work as a substitute in equal measure, though they produce a chunkier, less uniform crumb texture. Steel-cut oats are too coarse and won't bind properly. Instant oats may make the base too dense.
How long do baked squares keep at room temperature?
Store covered with foil for up to 2 days at room temperature. Beyond that, refrigerate to prevent the filling from separating or the base from becoming stale. Refrigerated squares last 5 days total.