Preheat oven to 350°. Lightly spray a 13x9-inch baking dish with baking spray with flour.
In a medium bowl, beat butter and sugar with a mixer at medium speed until fluffy, 3 to 4 minutes, stopping to scrape sides of bowl. Add eggs, one at a time, beating well after each addition. Beat in lemon juice and vanilla.
In a medium bowl, whisk together flour, gelatin, baking powder, baking soda, and salt. Gradually add flour mixture to butter mixture alternately with buttermilk, beginning and ending with flour mixture, beating just until combined. Stir in crushed strawberries; pour batter into prepared pan. Top with diced strawberries. In a small bowl, combine sliced strawberries and remaining 1 tablespoon sugar; set aside.
Bake until a wooden pick inserted in center comes out clean, 30 to 35 minutes. Let cool completely. Spread Cream Cheese Frosting on top of cake. Garnish with macerated strawberries, if desired.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/strawberry-sheet-cake/