In a large bowl, whisk together the Redpath® Dark Brown Sugar, all-purpose flour, and salt until thoroughly combined. Set aside.
In a small heavy-bottomed saucepan, combine the evaporated milk and butter. Place over medium heat and stir until the butter is melted. Immediately pour the milk mixture over the brown sugar mixture. Whisk gently for about 30 seconds to combine.
In a small bowl, whisk together the egg, egg yolk, and vanilla extract. Quickly whisk the eggs into the brown sugar mixture until smooth.
Place the chilled pie crust onto a baking sheet. Carefully pour the brown sugar filling through a fine-mesh sieve into the crust.
Carefully place the filled pie into the preheated oven; 35 to 40 minutes or until the filling is bubbling gently in the centre but has firmed up around the edges. The filling should wobble slightly when gently shaken.
Remove from oven and place on a wire cooling rack to cool completely. If a soft, runny filling is desired, serve at room temperature. If a firmer centre is desired, place cooled pie into the fridge to chill and set.