In a mixing bowl, beat together the butter, brown sugar, vanilla extract, and salt until the mixture is fluffy. This will take 2-3 minutes with an electric mixer or about 5 minutes if you’re mixing by hand. Add the flour all at once and stir it in carefully.

Press about 2/3 of the dough into an even layer in the bottom of a 9″x9″ baking dish. Reserve the rest for topping the bars.

Wash the strawberries thoroughly, then cut off the green tops. Slice the strawberries, or chop them into small pieces. Cut a fresh lemon in half.

Place the berries in a bowl and gently stir in the sugar, a splash of vanilla extract, and juice half of the lemon into the bowl. Set the berries aside for about 30-60 minutes. This is called macerating and will create a sweet juice for the berries to cook in.

Once the strawberries are juicy, spread them over the shortbread crust. Pour any juice left in the bowl over the top of them.

Use the remaining shortbread cookie dough to create a crumbly topping. With your fingers, break off little bits of the dough and spread them over the berries, making sure that there are still places where the strawberries shows through.

Preheat the oven to 350°F/180°C. Place a rack in the center of the oven.

Once it has preheated, place the pan in the oven and bake it for 45-50 minutes, or until the topping is beginning to turn golden brown and no longer looks doughy. The berries should be darker and have a jammy, thickened look.

Remove the pan from the oven and allow it to cool completely before cutting it up–this allows the filling to set. Cut in four strips in one direction, then turn the pan and cut it the other direction to create squares. With a spatula, carefully remove them from the pan.

Store the bars in an airtight container at room temperature. They will keep to 3-4 days.