Mix up butter and cookie crumbs and press into a baking pan - 8x8 or 9x9 work well. It helps to cover pan first with foil and cooking spray first. At 350 degrees, bake crust for fifteen minutes while preparing filling.
In a small bowl, place one cup of white chocolate chips and set aside.
With remaining three cups of white chocolate chips, place them in a medium saucepan over medium low heat. Add the sweetened condensed milk, stirring, until melted and milk is combined.
While chips and sweetened condensed milk heats and heats in pan, microwave and heat, on 50% power, the other bowl of chips for about 1-2 minutes, stirring each 30 seconds.
As the sweetened condensed milk and chips melt, add lemon extract and food coloring. Working quickly, pour over crust. Meanwhile, stir melted chips from microwave and fluff together (microwave for a few minutes more if needed).
Next, drop spoonfuls of chip/fluff mixture into the pie crust on top of the lemon and swirl into the top. Allow the pie to cool on the counter somewhat then place in the fridge to chill completely until set. Cool on counter for about 10-15 minutes and then chill until set.
Notes from site:
If the cookies you're using for the crust are particularly buttery, you won't need to use as much butter, and vice verse. Use your judgement. The crust should come together easily when you press it into the pan - if not, add a bit more.