Preheat your oven to 350°F (175°C) and bake the pie crust until golden brown for about 10–12 minutes. Let cool completely.

In a saucepan, whisk together brown sugar, milk, egg yolks, and cornstarch over medium heat. Cook while stirring for about 5–7 minutes until thickened.

Remove from heat and stir in vanilla extract. Pour the butterscotch filling into the cooled pie crust.

In a clean bowl, beat egg whites until soft peaks form, about 2–3 minutes. Gradually add sugar and continue to beat until stiff peaks form.

Spread meringue over the filling, ensuring it touches the edges. Create peaks for texture.

Bake in the oven for about 10 minutes, or until meringue is golden brown. Watch carefully.

Cool completely at room temperature for best texture and flavor before slicing and serving.