Preheat oven to 350 degrees F. Grease and flour a 9 by 9-inch square baking pan and set aside.

To make the topping, in a large bowl, combine the flour, brown sugar, salt and cinnamon until evenly combined. Add the cold butter and rub with your fingers until the mixture resembles coarse crumbs, the size of peas. You can also do this with a pastry blender, two knives or a potato masher. Stir in the pecans and oats, set aside.

To make the cake, cream together the peanut butter, butter, and sugar in an electric mixer on high until fluffy and creamy, about 5 minutes. Stir in the eggs, one at a time, making sure to mix well after each addition. Stir in the vanilla extract.

In a medium bowl, sift or whisk together the flour, salt, and baking powder. Add the dry ingredients alternating between the buttermilk, beginning and ending with the dry ingredients. Make sure to mix just until combined after each addition. Do not over mix.

Pour half of the batter into the prepared baking pan, and smooth out into an even layer. Top with the strawberry preserves and spread out as well to almost the edges. Top with the remaining batter and spread once more. Give the pans a few raps on the counter to dislodge any air bubbles. Sprinkle the crumb topping on top, making sure to cover the top completely.

Bake until a toothpick inserted in the middle comes out clean, about 30 to 35 minutes. Remove from oven and let cool completely before slicing and serving. Leftovers can be stored at room temperature for up to 2 days or for 4 days in the fridge. Enjoy!