For the Crust:
In the bowl of a food processor, combine Samoa Girl Scout Cookies and Trefoil Cookies. Pulse until cookies resemble sand.
Remove cookie crumbs to a medium bowl and stir in enough melted butter to form a shaggy mix.
Press cookie/butter mixture into the bottom of a 8" pie pan, creating a crust across the bottom and slightly up the sides of the pan.
Set aside.
Clean the bowl of the food processor and pulse the Savannah Smiles Girl Scout Cookies. Place the lemony crumbs in a small bowl and set aside to use as topping for the pie.
For the Ice Cream:
Place the milk, heavy cream and zest from two of the lemons into a medium saucepan and set over medium heat. Bring the mixture just to a simmer, stirring occasionally, and remove from heat.
In a medium mixing bowl, whisk the egg yolks until they lighten in color. Gradually add the sugar and whisk to combine. Add the oil and whisk thoroughly. Temper the warm cream mixture into the egg mixture by whisking in small amounts, approximately 1 tablespoon at a time, until about a 1/3 of the cream mixture has been added. Pour in the remainder of the cream and stir to combine. Return the mixture to the saucepan and place over medium-low heat. Continue to cook, stirring frequently, until the mixture thickens slightly and reaches 170 to 175 degrees F, approximately 5 to 7 minutes. Strain the mixture through a fine mesh strainer into a container and place in the refrigerator uncovered. Allow to sit uncovered until it is cool enough not to form condensation on the lid. Cover and store for 4 hours, up to overnight, or until the temperature reaches 40 degrees or below.
Pour into an ice cream maker and process according to the manufacturer's directions, approximately 25 to 35 minutes.
Pour ice cream mixture over cookie crust and sprinkle Savannah Smiles Cookie Crumbs across the top. Place in the freezer for 3 to 4 hours to allow ice cream to harden.
Remove from the freezer and garnish with remaining lemon zest. Allow pie to sit for 5 to 10 minutes before serving. Cut into slices and enjoy!