Preheat oven to 325°. Spray a 13×9-inch baking pan with baking spray with flour. Line with parchment, letting excess extend over sides.
Pour 1 cup boiling water into a small, heatproof bowl. Add tea bags; cover and let stand for 10 to 15 minutes. Remove tea bags, squeezing to release liquid from bags. Let cool completely.
In a large bowl, whisk together melted butter and sugars until well combined. Whisk in tea, eggs, milk, and vanilla until well combined.
In a medium bowl, whisk together flour, baking powder, salt, and baking soda. Slowly add flour mixture into tea mixture, folding until just combined. Pour batter into prepared pan, smoothing top with an offset spatula.
Bake until a wooden pick inserted in center comes out clean, 35 to 40 minutes. Let cool completely in pan on a wire rack. Using excess parchment as handles, remove from pan or serve in pan.
Top with Sweetened Whipped Cream. Garnish with lemon slices, if desired. Serve immediately.
Sweetened Whipped Cream
In the bowl of a stand mixer fitted with the whisk attachment, beat cream at medium-high speed until frothy. Slowly add sugar; beat until stiff peaks form. Use immediately.
Notes
*We used Lipton Iced Black Tea Family Size tea bags.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/sweet-tea-cake/