Preheat oven to 350°F, spread pecans on a rimmed baking sheet. Toast for 5 minutes until fragrant and lightly golden. Remove and set aside.

In a heavy saucepan over medium heat, combine granulated sugar, brown sugar, and butter. Stir constantly until melted and mixture bubbles, about 3–4 minutes.

Remove from heat briefly, stir in heavy cream and vanilla extract. Return to medium, gently swirl until smooth caramel forms, about 2 minutes.

Add toasted pecans, stirring vigorously with a wooden spoon to evenly coat each nut in glossy caramel, about 1–2 minutes until mixture thickens.

Quickly transfer coated pecans to a parchment-lined baking sheet. Use a spatula to separate clusters. Allow pralines to cool and set completely, about 15 minutes.