Preheat the oven to 350 degrees F with the oven rack in the middle position. Lightly coat the sides and bottom of a 9-inch spring form pan with cooking spray. Line the bottom of the pan with parchment paper cut to fit. Lightly coat the parchment with cooking spray.
To make the crust: In the bowl of a food processor fitted with a metal blade, add the graham crackers. Pulse until the graham crackers are crumbs the size of cornmeal. Add the sugar and butter and pulse to thoroughly combine. Press the crumbs onto the bottom and 2-inches up the sides of the prepared pan. Wrap the outside bottom of the pan with foil and set aside.
To make the filling: In the bowl of a stand mixer, add the ricotta cheese. Using the paddle attachment, beat the ricotta cheese until smooth. Add the sugar and beat to incorporate. Add the lemon juice, vanilla, lemon zest, and lime zest and combine. Pour in the heavy cream and beat to combine. Add the eggs, 2 at a time and mix well to incorporate. Add the flour and salt and combine.
Pour the batter over the prepared crust and put the pan into the oven. Bake for 1 hour and 15 minutes. Turn off the oven and leave the door slightly ajar by inserting a wooden spoon between the oven and the door. Let the cheesecake sit in the oven for 45 minutes, remove it, and set it on a rack to cool. When it is completely cool, cover the pan with plastic wrap, and refrigerate at least 2 hours or overnight.
To make the curd topping: In a heavy-bottomed saucepan, add the egg and yolks. Add the sugar, lemon zest, lime zest, and salt, and whisk to combine.
Put the pot over medium heat and whisk in the lemon juice and lime juice. Add the butter and whisk over medium heat until the butter is melted. Continue to whisk the mixture until the curd thickens, about 5 minutes.
If you prefer smooth curd, strain the curd to remove the zest. Put the curd into a bowl and place plastic wrap directly onto the surface of curd to prevent a skin from forming. Let the curd cool for 10 minutes and refrigerate.
When you are ready to decorate, remove the cheesecake and curd from the refrigerator. Spoon the curd gently onto the top of the cheesecake. Let the curd set for 15 minutes while you make the confetti.
To make the confetti: Wash the lime and lemon. Peel wide strips of zest off each fruit being careful not to get any of the bitter pith.
Use a clean one-hole punch to punch out small circles out of the zest. Alternately, put the zest strips onto a cutting board and punch out circles using a metal frosting tip with a 3/8-inch opening. Scatter the confetti, peel-side up, over the top of the curd. Return the cheesecake to the refrigerator until ready to serve.
Remove the cheesecake from the refrigerator 10 minutes before serving. Run a butter knife around the edges of the pan and remove the sides. Gently run a butter knife between the parchment liner and the cheesecake. Ease the cheesecake onto the serving platter. To store the leftover cheesecake, cover with plastic wrap, and refrigerate.
For the crust you can substitute cookie crumbs for graham cracker crumbs. If the ricotta cake cracks on cooling, the curd will cover the crack.
Recipe courtesy of Marilynn and Sheila Brass