Preheat oven to 350˚ F. Spray a 9 x 13-inch pan with baking spray. Line with parchment paper, leaving a 2-inch overhang on long sides. Spray parchment paper lightly. Place prepared pan on a sheet pan (this will help keep the bottom from getting too brown as this does bake for an hour).

To make the streusel, whisk together butter, sugar and salt. Add flour and mix with a fork until large crumbs form. If mixture is too wet and crumbs are not forming, add a bit more flour (this can vary due to the water content of your butter.) Refrigerate until ready to use.

For the strawberry layer combine strawberries, sugar and flour in a medium bowl. Set aside. Don't try to use food processor, as the berries will turn into a liquid mess

In another medium bowl, whisk 1 ½ cups flour, baking powder, and salt. Set aside

For the cake layer, beat butter and confectioners' sugar with an electric mixer until light and fluffy. Then beat in eggs, one at a time.

With mixer on low, beat in vanilla, then flour mixture.

Spread batter in prepared pan. Sprinkle with strawberry mixture and top with streusel.

Bake cake until golden and a toothpick inserted in center comes out with moist crumbs attached, 55 to 65 minutes. Cover with foil during last 15-20 minutes of baking if the top is getting too brown. Let cool completely in pan. Using paper overhang, lift cake from pan. Cut into bars. Sprinkle with powdered sugar, if desired.