Mum-Mum's Butterscotch Pie

In a medium saucepan, whisk together the milk, brown sugar, and cornstarch until well combined. (2 minutes)

Place the saucepan over medium heat. Cook, whisking constantly to prevent scorching, until the mixture thickens and coats the back of a spoon. (8-10 minutes)

Remove about 1/2 cup of the hot filling mixture and slowly drizzle it into the beaten egg yolks, whisking continuously to temper them. This prevents the eggs from scrambling. (1 minute)

Pour the egg yolk mixture back into the saucepan. Bring the mixture to a gentle boil, then reduce the heat to low and continue cooking, whisking constantly, until the filling thickens to a pudding-like consistency. (5-7 minutes)

Remove the saucepan from the heat. Stir in the butter and vanilla extract until the butter is fully melted and the mixture is smooth and glossy. (2 minutes)

Cover the butterscotch filling with plastic wrap, pressing it directly onto the surface to prevent a skin from forming. Allow the filling to cool completely at room temperature, stirring occasionally. (1-2 hours)

For faster cooling, place the covered filling in an ice bath. Stir occasionally until cooled. (30-45 minutes)

Once the filling is completely cooled, pour it into the pre-baked pie crust and spread evenly. Set aside while you prepare the meringue. (5 minutes)

Preheat your oven to 350 degrees F (175 degrees C). (10 minutes)

In the clean bowl of a stand mixer fitted with the whisk attachment, or using an electric mixer, beat the egg whites and cream of tartar together until soft peaks begin to form. (3-5 minutes)

Gradually add the granulated sugar, one tablespoon at a time, while continuing to beat the egg whites. Continue beating until stiff, glossy peaks form. The meringue should hold its shape. (5-7 minutes)

Using a spatula, gently spread the meringue over the butterscotch filling, ensuring that it completely covers the filling and seals to the edges of the crust. Create decorative swirls or peaks with the spatula. (5 minutes)

Bake in the preheated oven until the meringue peaks are lightly golden brown. (12-15 minutes)

Remove the pie from the oven and let it cool to room temperature on a wire rack. (1 hour)

Once cooled, transfer the pie to the refrigerator and chill completely before serving. (at least 4 hours)