Preheat the oven to 350°F. Liberally spritz a 13 x 9 inch metal baking pan with cooking spray. Set aside.
In a heavy bottomed saucepan melt the butter. Add the brown sugar. Cook over medium stirring constantly until the sugar has dissolved. Remove from the heat and cool to warm.
Use a hand mixer to beat the eggs into the warm mixture one at a time beating well after each addition then add the vanilla.
In a medium bowl use a whisk to sift together the flour, baking powder and salt.
Gradually beat the dry ingredients into the creamed butter-brown sugar mixture.
Assemble: Pour 1/2 of the batter into the pan. Top with 1/2 of the Rolo candies and 1/2 of the toasted pecan pieces.
Pour the remaining batter on top. Roughly chop the remaining Rolo candies and sprinkle over the batter. Top with a sprinkle of pecans. [Reserve 2 Tbsp for garnishing.]
Bake for 40 minutes or until the top is golden and a toothpick shows moist crumbs. Test the batter, the melted caramel will be gooey. Cool the bars in the pan on a cooling rack.
Chocolate Drizzle: In a microwave safe bowl, melt together the chocolate chips and vegetable shortening. Heat in 20 second increments stopping to stir each time. Repeat until smooth.
Drizzle over the cookie bars and garnish with pecans.