- Add the Kerrygold salted butter to a small saucepan, over medium heat. Melt the Kerrygold butter, and continue to cook, whisking constantly, until it smells nutty, and begins to brown, about 6-7 minutes. Pour into a heatproof bowl, and set aside to cool slightly.
- Make the filling: Add the frozen strawberries, strawberry preserves, and lemon juice to a small sauce pan, and cook on medium heat until the strawberries have mostly broken down. Use the back of a spoon to gently smash the strawberries. This should take about 10 minutes. Set aside to cool.
- Preheat the oven to 350 degrees F. In a medium bowl, add the browned Kerrygold butter, brown sugar, vanilla extract, kosher salt, 1 cup of the oats, and flour. Use a spoon to mix, until dough comes together, is crumbly, and there are no dry patches of flour.
- Line an 8×8″ baking pan with parchment paper. Pour 2/3 of the mixture into the prepared baking pan. Use the bottom of a cup or measuring cup to press the mixture down into an even layer. Spread the strawberry filling over the bottom crust.
- Add the remaining 1/2 cup of oats to the remaining dough, and evenly sprinkle the crumbly mixture on top of the strawberry filling. Bake for 50-60 minutes, until lightly golden brown. Allow to cool completely, then slice into 9 large square bars, or 18 smaller rectangle bars.