Preheat the oven to 325°F and lay out all of the 4” tins on a baking sheet.
Add the butter, light brown sugar, sugar, oil, eggs, and vanilla to the bowl of a stand mixer fitted with a paddle attachment. Beat at medium to high speed until it has become light and fluffy, about 3 to 4 minutes.
1 cup salted butter, ¾ cup light brown sugar, ½ cup granulated sugar, ½ cup canola or vegetable oil, 2 large eggs, 1 Tablespoon vanilla extract
Add the flour, 1½ cups of the graham cracker crumbs, cornstarch, baking powder, and salt to the bowl with the butter. Beat again on medium speed until everything has combined.
2½ cups all-purpose flour, 2½ cups graham cracker crumbs, 2 teaspoons cornstarch, 1½ teaspoons baking powder, 1 teaspoon salt
Pour the remaining 1 cup of graham cracker crumbs into a bowl or plate, set aside.
2½ cups graham cracker crumbs
Create ¼ cup sized balls of dough, roll each ball into the graham cracker crumbs. Place each ball into one of the 4” tart tins. Using the flat bottom of a cup or measuring cup, flatten the balls of dough into the tin, pushing deep enough to create a cavity. If you find the cup is sticking to the dough, dip the cup into some graham cracker crumbs before pressing.
Bake at 325°F for 12 to 15 minutes or until lightly golden. Remove from the oven and let cool.
While the cookies are cooling you can make the filling. Start by whipping the heavy whipping cream in a stand mixer until it has reached stiff peaks. Scrape the whipped cream into another bowl and set aside.
1½ cups heavy whipping cream
In the mixer bowl, add the softened cream cheese and beat on medium-high speed until smooth, then while the mixer is running slowly stream in the sweetened condensed milk.
28 ounces sweetened condensed milk, 16 ounces cream cheese
Mix in the sour cream until fully incorporated.
½ cup sour cream
Add the lime juice to the cream cheese mixture and beat for a couple of minutes on medium-high speed until smooth and creamy.
10 ounces lime juice
Fold the whipped cream into the filling mixture.
When the cookies have cooled, scoop the mixture into each cookie so the filling is mounded a bit on top.
Garnish with a thin wedge of lime, lime zest, graham cracker crumbs, and a star of whipped cream.
whipped cream, lime wedges, lime zest, graham cracker crumbs
Serve chilled. Store in a single layer in an airtight container.