Blueberry Oatmeal Squares (With Variations)

These wholesome bars are a lot like the Starbucks blueberry squares. So yummy and relatively healthy, at least compared to chocolate or ice cream (or so I tell myself, lol). The best thing about this recipe is the oatmeal base and crumble topping. It is so versatile and makes enough for a generous amount on the top and bottom because c'mon... isn't that everyone's favorite part?!

I use this same recipe with a multitude of different fillings (Some of my favorite variations are listed below the recipe). The blueberry filling is from Canadian Living Magazine - August 2007 (Go Canada!) I have also successfully used the same recipe with strawberries.

Blueberry Oatmeal Squares
9x13" Pan

Base/Topping:
2 cups quick cooking oats
1 cup all-purpose flour
1 cup brown sugar
1/2 teaspoon salt
1/2 teaspoon baking soda
3/4 cup butter, softened

Filling (also try variations below):
3 cups fresh blueberries
1/2 cup sugar
1/3 cup orange juice
4 tsp cornstarch

1. Filling: In saucepan, bring blueberries, sugar and orange juice to boil; reduce heat and simmer until tender, about 10 minutes. Whisk in cornstarch and boil, stirring, until thickened, about 1 minute. Place plastic wrap directly on surface; refrigerate until cooled, about 1 hour or up to 1 day before using.
2. Base/Topping: In a large bowl, stir together the oats, flour, brown sugar, salt and baking soda. Cut in the butter to form a crumbly mixture. Reserve 1 1/2 cups of the crumbs, and pat the rest evenly into the bottom of a greased 9 x 13 inch pan.
3. Bake at 350 degrees F until light golden, about 40-45 minutes. Let cool completely on rack as these cut better when they are fully set. (Make-ahead: Cover and refrigerate for up to 2 days or overwrap with heavy-duty foil and freeze for up to 2 weeks.)

Filling Variations

1. PEANUT BUTTER CARAMEL
***You must try this. You will not be disappointed!*** Mix together 1 (14 oz) can sweetened condensed milk and 3/4 cup peanut butter. Spread this over the oatmeal base then sprinkle with 1 cup semi-sweet chocolate chips. Cover with topping and bake.

2. CARAMEL APPLE
Mix 4 cups peeled and sliced apples with 1 tbsp lemon juice, then toss with 3 tbsp flour. Spread the apple mixture evenly over the base. In a small saucepan over medium heat, melt 14 oz. caramel candies, stirring frequently until smooth. Drizzle the melted caramel evenly over the apples. Cover with reserved oat mixture. Press down lightly and bake at 400F for 30-35 minutes or until topping is golden and apples are tender.

3. CHOCOLATE: In a heavy pot, melt 2 tablespoons butter and 1 cup chocolate chips. Add 2/3 cup evaporated milk and 1/4 cup of the white sugar. Bring to a rolling boil, stirring constantly until slightly thickened. Remove from heat. Stir in 1/2 cup nuts (I like pecans or walnuts) and cool slightly before spreading over base.

4. RASPBERRY
Spread with 1/2 cups Raspberry Jam