This truly is Susan's Perfect Pecan Pie—a classic dessert perfected over a decade of testing to deliver a filling that is never too runny, never too sweet, and absolutely loaded with pecans.
Preheat oven to 450°F. Line a half sheet pan with non-stick aluminum foil and set aside.
Place room temperature butter in a large bowl and beat on medium speed with an electric hand mixer for two minutes. Next, add both brown sugars and beat it on medium speed for two minutes. Then, add the Karo syrups and vanilla extract, beat for two minutes.
Crack all of the eggs into a separate bowl, then add them to the bowl with the filling. Beat for two minutes until incorporated. Then, scraped down the sides of the bowl and beat for an additional minute.
Place the frozen pie shells on the prepared sheet pan. Sprinkle 1 ½ cups of toasted pecan pieces into each pie shell. Give the filling a stir, then ladle it over the pecans until mixture reaches the line in the shell where the fluting starts. Repeat with remaining shell. Bake at 450° F for 10 minutes. Reduce heat to 350° F and continue baking for another 35-40 minutes. Remove from oven; cool completely on wire rack.
Refrigerate the leftover filling until ready to make mini pecan pies. Once the large pies have finished baking, reduce the oven temperature to 325°F. Line a half sheet pan with non-stick aluminum foil. Place frozen mini pie shells on the prepared pan and add one tablespoon of toasted pecan pieces. Then, add two tablespoons of filling to each pie shell. Bake in a 325°F oven for 40 minutes. Remove from oven; cool completely on wire rack.
Tips/Notes
If you don't want to make any mini pies, I recommend using two deep dish pie crusts in place of regular crusts. Then, add about 10 minutes of baking time, or until they pass the "jiggle" test.
To toast pecan pieces, spread them out on a half sheet pan with sides and bake in a 350°F oven for 10 minutes.