French for "crunch in the mouth," croquembouche is a tower of cream puffs held together by hot caramel. Martha makes the dessert even more showstopping by turning the pastries pink and filling them with strawberry buttercream.
Pate a Choux:
Preheat oven to 450 degrees with rack in bottom third. Line three rimmed baking sheets with parchment. In a medium saucepan, combine butter, sugar, salt, and 1 cup water over medium heat; bring to a boil. Remove from heat. Using a wooden spoon, quickly stir in flour. Cook over medium-high heat, stirring constantly, until mixture pulls away from sides of pan and a film forms on bottom, about 3 minutes.
Transfer to the bowl of an electric mixer fitted with the paddle attachment. Beat on low speed until slightly cooled, 1 1/2 to 2 minutes. With mixer on low, add eggs, one at a time, beating until each is fully incorporated and a soft peak forms when you touch dough with your finger.
Transfer about half the dough to a large pastry bag fitted with a 5/8-inch plain tip (such as Ateco #808). Pipe into rounds, about 1 1/4 inches in diameter, onto prepared sheets, spacing about 2 inches apart. Smooth peaks with a wet finger, rounding tops to ensure even rising. Repeat with remaining half of dough. Place baking sheets in freezer while you repeat with remaining dough and make craquelin topping.
In the bowl of an electric mixer fitted with the paddle attachment, beat together butter and sugar on medium speed until fluffy, about 4 minutes. Beat in flour and salt. Add pink food color, a drop at a time, until desired color is reached. Roll out topping between two sheets of parchment to an 1/8-inch thickness. Transfer to a baking sheet and freeze 30 minutes.
Using a 1-inch round cutter, cut out 72 rounds of craquelin dough and place one on top of each puff. Return to freezer.
Transfer one baking sheet of puffs to oven; reduce oven temperature to 350 degrees. Bake until bottoms are golden brown and tops are crackled and crisp but not browned, 25 to 30 minutes. Repeat process with remaining baking sheets. (For crispier puffs, remove from oven after baking and use a small paring knife to create a small slit in the base of each puff. Turn off oven; return puffs to oven until crisp, 5 to 8 minutes. Let cool completely.)
Combine egg whites, sugar, and salt in the heatproof bowl of an electric mixer set over (not in) a pot of simmering water. Whisk until sugar is dissolved and mixture is warm to the touch and feels completely smooth when rubbed between fingertips.
Transfer bowl to mixer fitted with the whisk attachment. Starting on low speed and gradually increasing to medium-high, beat until stiff (but not dry) peaks form. Continue beating until mixture is fluffy and glossy and bottom of bowl is cool to the touch, about 10 minutes. Reduce speed to medium-low and beat in butter, a few tablespoons at a time, until combined. Scrape down sides of bowl and continue beating until completely smooth. Beat in jam. Remove bowl from mixer and fold in chopped strawberries. Transfer to a pastry bag fitted with a coupler and a filling tip (such as Wilton #230).
Insert pastry-bag tip into base of each puff; fill. Return filled puffs to baking sheets in a single layer as you work.
Prepare an ice-water bath. In a small saucepan over medium heat, bring sugar and 1/4 cup water to a boil, washing down sides of pan often with a wet pastry brush to prevent crystals from forming. Cook, without stirring, until sugar dissolves, about 5 minutes. Increase heat to high and cook, swirling pan gently to color evenly, until caramel is light amber, about 5 minutes. Remove from heat and dip bottom of pan in ice-water bath for a few seconds to stop the cooking. Use immediately.
Working quickly, dip bottom of each filled puff in caramel (be very careful not to burn your fingers) and adhere puffs closely together in circular pattern, working upwards from the base to top of croquembouche mold.
Use macarons and meringue kisses to fill in spaces between puffs, as needed.
Martha used a 15 3/4-by-10-inch croquembouche mold. If using one this size, you'll need to make 3 batches of the pate a choux recipe and 2 batches of the craquelin topping recipe.