Cookies

1. Combine the butter, brown sugar and white sugar together in a large mixing bowl and beat until light and fluffy
2. Add the egg and whisk until combined
3. Whisk the flour and baking powder together in a small mixing bowl and add to the wet ingredients
4. Mix until just combined, cover with cling wrap, and chill for 1 hour or until firm

Mochi filling

1. Combine the glutinous rice flour and sugar in a medium heat-proof mixing bowl, whisk to combine
2. Add the milk and whisk until well combined
3. Cover with cling wrap and microwave on high for 1 minute 
4. Remove from the microwave and mix
5. Recover and microwave for 1 minute bursts until the dough is no longer milky
6. Add the vegetable and mix roughly (it won't be fully incorporated), and cool
7. Once cooled use oiled or gloved hands to knead the mochi until the oil is fully absorbed and the dough is stretchy
8. Divide into 9 portions and place on a sheet of baking paper, set it aside.

Assembly

1. Preheat the oven to 180C/355F, and line a baking tray with baking paper
2. Once the cookie dough has chilled divide it into 9 portions
3. Roll each portion into a ball and press between your palms to flatten
4. Place a ball of mochi in the centre and bring the edges of the dough together to enclose the mochi
5. Roll the dough into a smooth ball and place on the lined baking tray
6. Top each cookie with chunks of chocolate, then bake for 13-15 minutes, or until lightly golden brown.
7. Cool for 15 minutes, before enjoying