2 1/2 cups pecan halves, broken in pieces
1/2 cup unsalted butter
2 4-oz bars bittersweet chocolate, broken into small pieces
3/4 cup sugar
2 large eggs
3/4 cup all-purpose flour
2 cans (14-oz each) sweetened condensed milk
1/4 tsp kosher salt
20 thin pretzels
Arrange oven racks to divide the oven into thirds. Heat oven to 350-degrees.
Line a 9X13-inch baking pan with nonstick foil, leaving a 3-inch overhang on two sides.
Spread the pecans in a single layer on a rimmed baking sheet and roast until toasted and fragrant, 8 to 10 minutes.
Meanwhile, place butter and half the chocolate in a medium saucepan and cook, stirring over medium-low heat until melted. Remove from the heat and whisk in sugar then eggs. Add the flour and stir until smooth.
Spread the batter into the prepared pan and bake until a wooden pick inserted in the center comes out clean with no moist crumbs attached. This should take about 12 to 15 minutes.
Meanwhile, place sweetened condensed milk in a second medium saucepan. Whisking often, bring to a simmer over medium-low heat. Gently simmer, whisking constantly, until very thick and light golden brown in color, 15 to 20 minutes.
Add the salt and 1 1/2 cups toasted pecans to the saucepan and stir to coat. Spread over the crust. Sprinkle with the remaining chocolate and pecans. Place the pretzels on top.
Allow to set at room temperature until firm. Using the foil overhangs, transfer to a cutting board and cut into 36 pieces.