Line a baking sheet with parchment paper or a silicone mat. Have a tablespoon or cookie scoop ready.
In a medium heavy-bottomed saucepan, combine 1 cup granulated sugar, 1 cup brown sugar, ½ cup heavy cream or evaporated milk, 4 tablespoons unsalted butter, and a large pinch of sea salt.
Cook over medium heat, stirring occasionally, until the mixture comes to a boil. Wash down crystals that might form around the saucepan with a wet brush to prevent crystallization.
Attach a candy thermometer and cook, stirring often, until the mixture reaches 235–240°F (112–115°C), soft ball stage. If you don’t have a thermometer, test by dropping a little into cold water; it should form a soft ball that flattens when removed.
Remove from heat and let cool for several minutes, until it reaches 150°F.
Stir in 1 teaspoon vanilla extract and 2 cups pecans, and immediately beat with a wooden spoon for about 2 minutes until the mixture thickens slightly and looks slightly grainy but still glossy.
Working quickly, drop spoonfuls of the praline mixture onto the prepared baking sheet. They will spread slightly and set as they cool.
Top each with a whole pecan if you want to, before letting them cool completely until firm. Store in an airtight container at room temperature for up to a week.