Preheat the oven to 350°. Line a 9-inch square baking pan with parchment paper, allowing 2 inches of overhang on 2 opposite sides. Spray the paper with vegetable spray. Spread the pecans in a pie plate and toast for about 8 minutes, until fragrant. Let cool, then coarsely chop the nuts.
In a skillet, cook the bacon over moderate heat, turning once, until crisp, 6 minutes. Drain on paper towels and let cool; reserve 3 tablespoons of the fat. Finely chop the bacon.
In a saucepan, combine both chocolates with the butter and stir over very low heat, until melted; scrape into a large bowl. Using a handheld electric mixer, beat in both sugars with the reserved 3 tablespoons of bacon fat. Beat in the bourbon. Add the eggs and salt and beat until smooth. Sift the cocoa and flour into the bowl and beat until blended.
Scrape the batter into the prepared pan and sprinkle the bacon and pecans on top. Bake for about 50 minutes, until the brownies are set around the edges but slightly wobbly in the center; a toothpick inserted into the center should have some batter clinging to it. Transfer the pan to a rack and let the brownies cool completely. Lift the brownies out of the pan using the parchment paper. Cut into squares or rectangles and serve.