Pre heat oven to 180c ff
Grease & line an 18 cm x 18 cm/7" x 7" baking tin & set aside.
Microwave 150 g of butter on high for 1 - 1 ½ mins or until melted (cover the bowl with a piece of paper/kitchen towel to keep your microwave clean).
Add raw caster sugar to butter, mixing to combine & melt sugar.
Add flour, mixing to combine, then press mixture into prepared tin, using a silicone spatula or similar to create an even layer (see notes).
Bake for 10 - 12 mins or until just cooked through then set aside.
Meanwhile prepare the topping by microwaving the remaining 100 g of butter on high for about 1 min, or until melted.
Add light brown sugar & vanilla paste to butter, mixing to combine & melt sugar.
Add chopped pecans to butter mixture & mix to combine.
Add eggs to butter mixture, mixing well to combine.
Pour butter pecan mixture over prepared shortbread base, evenly distributing pecans as best you can.
Bake for 25 mins or until centre of topping is cooked & set.
Allow to stand for 15 mins then cut into 16 squares.