Ingredients:
Crust

• 1 ½ cups  all-purpose flour
• 1 cup firmly packed dark brown sugar
• 1 ¼ cups rolled oats
• ¾ tsp salt
• ¾ tsp baking powder
• ½  tsp baking soda
• ½ tsp ground cinnamon
• ¾ cup unsalted butter, cut into 1-inch pieces

Filling

• ¼ cup firmly packed dark brown sugar
• 1 Tbsp lemon zest
• ½ tsp ground cinnamon
• 2 Tbsp all-purpose flour
• 1 pound raspberries, fresh or frozen
• ¼ cup lemon juice
• 2 Tbsp unsalted butter, melted and cooled
• ¼ tsp salt
• 8 Tbsp melted unsalted butter
• ½ tsp vanilla extract

Make it:
For the crust

1. Preheat oven to 350 degrees.
2. Butter an 8-inch pan and then line with a buttered parchment paper. Have the parchment reach a couple inches over the pan to easily remove the bars after they have baked. Remove the foil and turn the pan over and press the foil into the pan, smoothing it as best as you can. Lightly butter or spray the foil with nonstick spray.
3. Put all of the crust ingredients except the butter in a food processor. Pulse in short bursts until combined. Add the butter and pulse until the mixture forms loose crumbs.
4. Reserve 1 ½ cups of the mixture and set aside. Use the rest of the batter to spread into the pan as evenly as possible with a spatula or your hands.
5. Bake the crust for 12-15 minutes or until golden brown. When finished, let cool while preparing the filling.

For the filling

1. In a medium bowl, whisk the sugar, lemon zest, cinnamon and flour together. Add the raspberries, lemon juice and butter and use your hands to gently toss until the raspberries are evenly coated by the mixture.  

To combine

1. Pour the filling mixture over the crust and then sprinkle the 1 ½ cups of reserved crust mixture on the top of the filling.
2. Bake for 35 to 45 minutes, making sure to rotate the pan every 15 minutes, until the top is golden brown, and the filling begins to bubble around the edges.
3. Let cool and cut into squares.

Notes: 

• The bars will keep in an airtight container at room temperature up to two days. You can freeze the bars as well for up to one month, letting them return to room temperature before serving.
• These bars can be made vegan and gluten-free by using gluten-free flour, gluten-free oats and vegan butter substitutes.
• You may substitute another type of berry, such as blackberry or marionberry!