Preheat the oven to 375 degrees F.

In a bowl, mix together the crumbs, sugar, and cinnamon. Add the butter and mix well. Using the back of a spoon, press evenly into the bottom and slightly up the sides of a 9-inch springform pan. Bake until golden, about 8 minutes. Remove from the oven and cool before filling.

In a cake mixer fitted with a paddle attachment beat the cream cheese and sugar on low speed until well incorporated, smooth and light, about 2 minutes. Add the eggs, one at a time, and lemon zest and continue to beat until well incorporated, scraping down the sides as necessary. Slowly add the ricotta cheese to the batter and mix until smooth.

Pour the batter into the prepared pan and bake in the middle of the oven until starting to set, about 45 minutes. Lower the oven temperature to 325 degrees F and cook for another 20 to 25 minutes. Remove from the oven, use a thin sharp knife and run the blade along the inside of the cake pan to loosen the sides. Loosen the outer ring, and let the cake cool in the pan on a wire rack. Once the cheesecake is cooled to room temperature, cover with plastic wrap and refrigerate until thoroughly chilled, at least 6 hours or overnight.

Remove the cake from the refrigerator and let come to room temperature before serving. Slice the cake and serve on dessert plates, with the Citrus Thyme Sauce drizzled over all.

Set a 10-inch saute pan over medium-high heat and add the butter, sugar, grapefruit, lemon, lime, tangerine and thyme. Once the butter and sugar have melted, about 2 to 3 minutes, remove the pan from the heat and add the cognac-based liqueur into the pan. Ignite with a long kitchen match and when the flames subside return the pan to the heat. Continue to cook until the sauce is slightly thickened, about 10 minutes. Remove from the heat and serve with the cheesecake.

Yield: about 2 cups