Melt the chocolate: Combine milk chocolate chips and butter in a microwave-safe bowl. Heat in 10 to 15 second bursts, stirring between each until melted and smooth.

Start the custard base: In a saucepan, whisk together sugar and cornstarch. Gradually whisk in whole milk. Cook over medium heat, stirring often until thick and bubbling.

Cook the base further: Reduce heat to low, cook for 2 more minutes while stirring to prevent sticking.

Temper the egg yolks: In a bowl, whisk a small splash of hot mixture into egg yolks. Slowly pour back into the saucepan while whisking.

Finish the filling: Return saucepan to low heat. Cook for 2 more minutes, then whisk in the melted chocolate and vanilla extract.

Fill the crust: Pour chocolate filling into prepared pie crust. Let cool completely.

Make the coconut pecan topping: In a saucepan, combine brown sugar, butter, heavy cream, and sweetened condensed milk. Cook over medium heat until sugar dissolves and mixture boils.

Temper egg yolks like before, then add to the saucepan. Stir to combine.

Thicken the topping: Cook for 2 to 3 minutes until mixture coats the back of a spoon. Stir in vanilla extract, coconut flakes, and pecans.

Assemble and chill: Spread topping over the cooled chocolate filling. Chill for 2 to 3 hours before slicing.