In a small saucepan, whisk together the sweetened condensed milk and egg yolk. Cook over medium heat, stirring constantly, until the mixture just begins to simmer. Continue cooking for about 2 minutes to safely cook the egg yolk. Remove from the heat.

Stir in the vanilla extract and maple extract until well combined. Set aside to cool slightly.

In a large skillet over medium heat, melt the butter. Stir in the brown sugar until dissolved. Add the chopped pecans and ground cinnamon, stirring to coat evenly. Cook for 2–3 minutes, allowing the pecans to become fragrant and lightly toasted. Remove from the heat and fold the warm pecan mixture into the sweetened condensed milk mixture. Stir until fully incorporated and let cool.

Using a stand mixer fitted with a chilled whisk attachment—or a hand mixer with chilled beaters—whip the cold heavy cream until stiff peaks form, about 3 minutes.

Gently fold the whipped cream into the cooled pecan mixture using a spatula. Continue folding until no streaks remain, being careful not to overmix so the mixture stays light and airy.

Pour the mixture into a loaf pan or freezer-safe container. Cover tightly with plastic wrap or a lid and freeze. For a soft-serve consistency: Freeze for 4–6 hours. For traditional scoopable ice cream: Freeze overnight.

Before serving, garnish with toasted chopped pecans or whole pecan halves, if desired.