Preheat your oven to 350°F (175°C). In a large bowl, combine the all-purpose flour, baking powder, salt, and granulated sugar. Add the softened unsalted butter and use a pastry cutter or your fingers to mix it into the dry ingredients until the mixture resembles coarse crumbs. Stir in the milk and vanilla extract until a soft dough forms.
Press the dough evenly into the bottom of your greased 9x13-inch baking pan. Bake for 18-20 minutes, or until the edges turn golden and a toothpick inserted into the center comes out clean. Remove from the oven and allow it to cool completely while you prepare the toppings.
In a chilled bowl, beat the heavy cream with an electric mixer until it starts to thicken. Gradually add the powdered sugar and vanilla extract, continuing to whip until soft peaks form. Be careful not to overwhip or the cream will become grainy.
Once the shortcake base has cooled, spread the whipped cream evenly over the top. Arrange the sliced fresh strawberries generously on the cream layer. For an extra touch, you can lightly press some strawberries into the cream for better adherence.
Place the pan in the refrigerator for at least 1 hour to let the layers set and the flavors meld. When ready, cut into bars and serve chilled. These bars are delightful on their own or paired with a scoop of vanilla ice cream.