Melt the butter and condensed milk: In a medium saucepan, combine the sweetened condensed milk and butter over low heat. Stir constantly for about 5 minutes, until the butter is fully melted and the mixture is smooth and creamy.

Mix in the sugar: In a large mixing bowl, sift the powdered sugar to eliminate any lumps, then gradually pour in the melted milk and butter mixture. Beat the mixture on low speed for about 2-3 minutes until you have a smooth, thick batter.

Fold in flavorful ingredients: Gently fold in the chopped walnuts, pure maple flavoring, and vanilla extract into the mixture.

Shape the truffle mixture: Scoop out roughly 1½ tablespoons of the mixture and roll it into smooth balls.

Melt the chocolate coating: In a microwave-safe bowl, combine the milk chocolate chips with a teaspoon of oil. Heat in the microwave in 45-second increments, stirring until the chocolate is completely melted.

Dip the truffles: Using a fork or dipping tool, immerse each firm truffle into the melted chocolate.

Allow to set: Let them sit at room temperature or in the refrigerator for about 30 minutes to set completely.

Store or serve: Once set, transfer the truffles to an airtight container and store in the refrigerator.