How to Make It
Line 2 rimmed baking sheets with parchment paper. Melt butter in a medium saucepan over medium-low. Add brown sugar, granulated sugar, and 1/2 cup of the cream; stir until sugar dissolves. Increase heat to medium, and simmer, using a heatproof rubber spatula to stir gently occasionally, until a candy thermometer reads 240°F to 250°F. (If mixture begins to crystallize, add 2 tablespoons of the cream, and cook, stirring, until it liquefies.) Stir in chopped pecans. Turn off heat, and give the mixture a final gentle stir, making sure to scrape the bottom and corners of the pan.
Using a wooden spoon, scoop about 2 tablespoons of the hot praline mixture onto the prepared baking sheets, leaving at least 1 inch between pralines. If mixture begins to crystallize in pan, add remaining 2 tablespoons of the cream, heat over medium, and stir until mixture looks creamy. Cool pralines on pans until solid, about 30 minutes. Transfer to an airtight container. (Pralines may be kept in the airtight container up to 3 days.)