Cube the butter into a bowl and melt in the microwave or on the hob over a pan of water until just melted.
Add the soft brown sugar and whisk together.
Next, whisk in the eggs until completely combined.
Add the flour and baking powder and mix until smooth - the batter will be quite liquid.
Add the white chocolate chips and fold in.
Assemble the blondie
Pour half of the blondie batter into your prepared tin and level off.
Spoon half the jam in large dollops over the blondie batter.
Top with half the Jammie Dodgers.
Pour the remaining blondie batter on top and level off.
Gently warm the remaining jam with a 15 second burst in the microwave, then spoon over the blondie batter. Swirl a little with the handle end of a spoon.
Top with the remaining Jammie Dodgers.
Bake for approximately 25 minutes until firm at the edges and a little under in the centre - it will continue to set as it cools.
Allow to cool in the tin, then chill overnight to make them easy to slice.
Slide the Jammie Dodger blondies onto a serving board and slice them into 12 squares (in a pattern of 3 by 4).