Chocolate Coconut Sheet Cake

Martha Stewart calls this her "foolproof cake"....well I guess so.... Made it and it was easy and moist, topping was a little sweet so I would start with 1 c powdered sugar, then add more to your taste. You could also use a boxed mix to save some time. As you can see..I had to make mine for tiny hands :)
softened butter, to butter pan
3/4 c unsweetened cocoa powder plus more for dish
1 1/2 c flour
1 1/2 c sugar
1 1/2 tsp baking soda
3/4 tsp baking powder
3/4 tsp coarse salt
2 lg eggs, lightly beaten
3/4 c low fat buttermilk
3/4 c warm strong brewed coffee
3 tbsp safflower oil
1 tsp vanilla
1 stick unsalted butter ,plus more for dish
2 c confectioners' sugar
6 tbsp cocoa powder
3 c finely shredded dried unsweetened coconut
2/3 c strong brewed coffee
1 tsp vanilla
whipped cream and toasted coconut for serving
chocolate eggs (opt)
Preheat oven to 350º. Butter a 9x13' baking dish, line bottom and sides with parchment paper, leaving an overhang. Butter parchment and dust with cocoa powder. Whisk together 3/4 c cocoa,flour, sugar, baking soda, baking powder and salt in a large bowl. Gather flour mix in to a mound and create a hole in center. Pour eggs,buttermilk, coffee, oil and vanilla into hole and whisk until smooth and combined. Pour into prepared dish and spread evenly with a spatula. Bake until set and toothpick inserted comes out clean, about 25 minutes.
 Meanwhile melt butter for topping in a small saucepan. Combine confectioners' sugar, cocoa and coconut in large bowl. Stir coffee and vanilla into butter and pour over coconut mixture. stir to combine and immediately spread over warm cake. Let cool completely on wire rack.
To serve, using parchment paper to transfer cake to cutting board. Cut and serve with whipped cream and toasted coconut (I used a cookie cutter for mini cakes)
Refrigerate up to 3 days.