Pre heat oven to 180 c ff / 355 f
Grease and line an 18 cm x 18 cm / 7" x 7" (base measurement) baking tin and set aside.
In a large bowl, melt butter on high for about 1 min in microwave until melted - careful it may splatter!
Add sugar and vanilla paste to melted butter, stirring to melt the sugar and combine.
Add flour and mix until completely combined, then remove 1/4 cup of the flour mixture and set aside.
Press the remaining flour mixture evenly into the base of the lined tin, pressing down well to create a smooth even base, then bake for 10 mins.
While base is baking, add the reserved flour base back to your original bowl, along with the peanuts & extra 1 tbsp of flour, then using your fingers crumble together to combine.
When base is finished baking, pour jam over base in a roughly even layer, making sure to go all the way to the edges.
Sprinkle crumb topping over the jam layer, then bake for a further 15 mins. Leave to cool in tin for a least 30 mins before slicing.