Directions

1. Preheat oven to 350°F. Coat a 13- x 9-inch baking sheet with cooking spray; set aside.
2. Whisk together milk and lemon juice in a glass measuring cup; set aside. Whisk together flour, baking powder, baking soda, and salt in a medium bowl; set aside. Beat granulated sugar and butter with a stand mixer fitted with the paddle attachment on medium-high speed until light and fluffy, 3 to 5 minutes, stopping to scrape down sides of bowl halfway through beating time. Add eggs, 1 at a time, beating for 30 seconds between additions. Add vanilla, and beat until combined, about 15 seconds. Add flour mixture in 3 additions alternately with milk mixture, beginning and ending with flour mixture, beating gently on low speed between additions until just combined. Pour batter into prepared baking sheet. Using a spatula, spread batter in an even layer; tap baking sheet 2 to 3 times on countertop to get rid of any air bubbles and to even out cake batter.
3. Bake in preheated oven until golden and a wooden pick inserted in center of cake comes out clean, 26 to 30 minutes.
4. Stir together granulated sugar, lemon juice, 2 tablespoons water, and saffron threads in a small saucepan over medium-low. Cook, stirring often, until sugar is dissolved, 1 to 2 minutes. Increase heat to medium, and bring to a simmer. Simmer, undisturbed, until slightly thickened, about 2 minutes. Remove from heat, and set aside.
5. Remove cake from oven; immediately brush lemon-saffron syrup generously over surface of cake using a pastry brush. Let cake cool completely in cake pan on a wire rack, about 1 hour and 30 minutes.
6. Stir together strawberries, granulated sugar, and lemon juice in a large bowl. Let stand at room temperature, stirring occasionally, until strawberries release their juices, 30 minutes to 1 hour.
7. Stir together 1 tablespoon boiling water and saffron in a small heatproof bowl. Let stand 15 minutes. Beat mascarpone, powdered sugar, and saffron mixture in a stand mixer fitted with the whisk attachment on medium speed until smooth, about 1 minute. With mixer running on medium speed, gradually add cream. Increase speed to medium-high, and beat until soft peaks form, about 2 minutes.
8. Dollop saffron-mascarpone whipped cream onto cooled cake, and spread in an even layer. Top with macerated strawberries; drizzle cake evenly with any juices remaining in bowl. Serve immediately.