Preheat oven to 300 degrees F. Spread pecan halves onto a baking sheet and toast for 6 minutes (mixing halfway through). Remove from oven and cool.
Take two baking sheets and line with parchment paper. Spray lightly with cooking spray to prevent sticking.
To a large pot add the brown and white sugars, butter, and milk and melt together over medium heat.
Stir in pecans and heat to 238 degrees F (check that candy thermometer!), stirring frequently.
Remove from heat and stir in vanilla and bourbon.
Continue stirring for about 3-4 minutes until thickened and creamy.
Quickly drop spoonfuls of the mixture onto the baking sheets, leaving room as the mixture will spread slightly.
Sprinkle lightly with sea salt.
Allow pralines to cool before removing from the baking sheets.