Coconut Sheet Cake with Hibiscus Sauce

Ingredients

• 1.5 teaspoons double-acting baking powder 
• 0.7 cup buttermilk 
• 1.8 cups cake flour 
• 0.3 teaspoon coconut extract 
• 4 tablespoons cream of coconut sweetened divided (such as Coco López)
• 1.5 ounces hibiscus petals dried
• 4 large egg whites 
• 1.5 cups cup heavy whipping cream chilled
• 1 teaspoon lime zest finely grated
• 0.5 teaspoon salt 
• 1.3 cups sugar 
• 1 cup coconut sweetened flaked lightly toasted
• 10 tablespoons butter unsalted room temperature ()
• 2 cups water 

Equipment

• bowl
• frying pan
• sauce pan
• oven
• knife
• whisk
• blender
• baking pan
• hand mixer
• spatula

Directions

1. Bring 2 cups water to boil in smallsaucepan. Stir in hibiscus flowers.
2. Removefrom heat; let steep uncovered 10 minutes.
3. Pour hibiscus mixture through fine-meshsieve set over bowl, pressing onsolids to extract all liquid; discard solids.Return hibiscus liquid to same saucepan.
4. Add sugar; bring to boil, stirring until sugardissolves. Boil gently over medium heatuntil liquid is reduced to 1 cup, 10 to 12minutes.
5. Remove from heat. Stir in lemonpeel, lime peel, and orange peel; steep 10minutes. Strain sauce into bowl. Cover; chilluntil cold, at least 2 hours. DO AHEAD: Can bemade 3 days ahead. Keep chilled.
6. Preheat oven to 350°F. Butter13 x 9 x 2-inch metal baking pan.
7. Whisk flour,baking powder, and salt in medium bowl.
8. Whisk buttermilk, egg whites, and coconutextract in another medium bowl. Usingelectric mixer, beat sugar and butter inlarge bowl until light and fluffy.
9. Add flourmixture to butter mixture in 3 additionsalternately with buttermilk mixture in 2additions, beating to blend well betweenadditions and occasionally scraping bottomand sides of bowl with rubber spatula.
10. Transfer batter to pan; spread evenly.
11. Bake cake until pale golden and testerinserted into center comes out with somecrumbs attached, 29 to 32 minutes. Coolcake completely in pan on rack. DO AHEAD: Can be made 1 day ahead. Cover pan tightlyand store cake at room temperature.
12. Using electric mixer, beatwhipping cream and 2 tablespoons creamof coconut in large bowl until peaks form.
13. Spread whipped cream over top of cake.
14. Drizzle 2 tablespoons cream of coconutover whipped cream. Using table knife,swirl cream of coconut throughout whippedcream.
15. Sprinkle toasted coconut over.
16. Cut cake into squares; transfer toplates.
17. Drizzle hibiscus sauce around cake.