½cupgraham cracker crumbsabout 4 sheets ground in a food processor, if using whole crackers
¼cupall-purpose flour
2tablespooncornstarch
1tablespoonsugar
1tablespoonbrown sugar
½teaspoonkosher salt
4tablespoonsbuttermelted
For the lemon curd:
2¼teaspoonsagar agar flakes
6tablespoonssugar
5tablespoonsfresh lemon juice
Finely grated zest from 2 lemons
3large eggs
6tablespoonschilled unsalted buttercut into ½-inch cubes
½teaspoonkosher salt
For the cake:
1½cupscake flour
1teaspoonbaking powder
3/4teaspoonkosher salt
8tablespoonsunsalted buttersoftened
1¼cupssugar
¼cuppacked light brown sugar
3large eggs
½cupbuttermilk or ½ cup milk with ½ tablespoon vinegar
½cupolive or grapeseed oil
1tablespoonvanilla extract
For the strawberry frosting:
3tablespoonsyour favorite strawberry jam
4tablespoonsunsalted butter
4-6tablespoonsconfectioners’ sugar
1/8teaspoonkosher salt
Additional ~1/2 cup strawberry jam of your choice
Instructions
For the cheesecake:
Preheat oven to 300° and grease an 8x8" pan. In a small bowl, whisk together cornstarch and salt. Add milk and egg, and whisk until smooth. With an electric mixer, beat cream cheese until smooth and fluffy, about 2 minutes. Add sugar and continue mixing 2 minutes more. Scrape the sides down, add the cornstarch mixture, and beat until batter looks smooth and runny. Pour the batter into the prepared pan and bake until set at the edges, but still slightly wobbly in the center. Check after 20 minutes and every 5 minutes after that (up to about 40 minutes). The surface should appear dull, not shiny, and should not be browned. Let cool completely before using (can be stored in the refrigerator for up to 1 week).
When you are ready to assemble the layer cake, turn the cheesecake out into a large bowl. Don’t worry about keeping it intact; it doesn’t matter how ugly it looks. Add the lemon curd and whisk together until completely smooth (or don't).
For the graham cracker crumb:
Preheat oven to 300 degrees and line a baking sheet with a silpat or parchment paper.
Whisk together all dry ingredients (graham cracker crumbs through salt. Drizzle butter over mixture and gently toss until you get a clumpy, just-moist, mixture with some pea-sized clumps. Pour mixture onto the prepared baking sheet and bake for 20 minutes, stirring once, or until crumbs just start to brown. Remove and cool completely.
For the lemon curd:
Sprinkle the agar agar flakes over 2 tablespoons cold water and let stand for 5 minutes. Meanwhile, blend the sugar, lemon juice and zest together until smooth, about 30 seconds. Add eggs and blend until smooth and foamy, about 15 seconds. Transfer the mixture into a small saucepan. Heat the mixture over low, stirring continuously with a wooden spoon until thickened and bubbles begin to break the surface. The curd should form a thick coat over your stirring utensil. Pour the mixture back into the blender along with the agar agar mixture, butter and salt and blend until smooth. Allow to cool and refrigerate until the curd is completely chilled, at least 1 hour. Curd can be stored in the refrigerator for up to 1 week, but bring to room temperature before assembly for easier spreading.
For the cake:
Preheat oven to 325 degrees and grease a 9x13 pan.
In a medium bowl, whisk together all dry ingredients (flour through salt). In another bowl, use an electric mixer to cream together the butter and sugars until light and fluffy, about five minutes. Beat in the egg until thoroughly combined. In a small bowl or measuring cup, whisk together the buttermilk, oil and vanilla. Stream mixture into the butter mixture while beating on low. Increase speed to high and beat for 5-6 minutes until mixture is pale and homogenous. It may look a little grainy, but you want the mixture to be as smooth as possible.
Once the mixture is homogenous, add the dry ingredients and mix on low until dry ingredients are just barely incorporated and you can still see streak of flour--do not overmix! Finish mixing the batter by hand until no floury streaks remain.
Pour batter into prepared pan and bake for 35-45 minutes, or until a tester inserted in the middle comes out clean. Cool completely before removing from pan.
Use a 6-inch cake ring or template to cut two 6-inch circles out of the cake. Line a six-inch cake pan with plastic wrap and press the remaining cake scraps firmly into the bottom to form your third cake layer. At this point, you can freeze tightly wrap each cake layer (leave the scrap layer in the cake pan) in plastic wrap for easier assembly later.
For the strawberry frosting:
In the bowl of a stand mixer fitted with the paddle, cream butter and sugar on medium-high speed until pale and fluffy, about 3 minutes. Add the jam and salt, then beat on low speed for 1 minute until smooth and fluffy.
To assemble:
Line a 6-inch cake pan with plastic wrap. Add one round of cake, then top with a layer of strawberry jam, 1/3 of graham cracker crumbs (reserving a small handful for garnish), then 1/2 of the lemon curd/cheesecake mixture (or whatever amount seems reasonable). Top with another round of cake, then repeat layers of filling. Top with final round of cake, spread with strawberry frosting and finish with more graham crumbs. Wrap in plastic wrap and freeze for at least 12 hours to set the layers. Let thaw at room temperature for at least 30 minutes, or in the refrigerator for up to 3 hours before serving.
Notes
Adapted from http://sugarandshake.com/cbtb-strawberry-lemon-layer-cake/