In a medium skillet, melt 1.5 tablespoons of unsalted butter over medium heat. Add 1 cup of pecan halves and stir frequently for 4-5 minutes until golden and fragrant. Transfer to a plate and set aside.

Line an 8x8-inch baking pan with parchment paper and lightly grease with butter to prevent sticking.

In a medium saucepan, melt 3 tablespoons of unsalted butter over medium heat. Cook until golden brown, about 5-7 minutes, then remove from heat and let cool slightly.

Set a heatproof bowl over a saucepan of simmering water. In the bowl, combine sweetened condensed milk, chopped white chocolate, and browned butter. Stir for about 5 minutes until melted and smooth.

Remove from heat and whisk in 1 teaspoon of vanilla extract, 1/4 teaspoon of salt, and 1/2 teaspoon of ground cinnamon. Gently fold in the buttered pecans.

Pour the mixture into the prepared baking pan and smooth the top. Chill in the refrigerator for at least 2 hours or until firm.

Lift the fudge out of the pan using the parchment paper, place it on a cutting board, and slice into squares. Store in an airtight container in the refrigerator for up to 1 month.