First crush the sweets/ candy. Separate the sweets/ candy by colour. Put the sweets/ candy into a ziplock bag and using a metal rolling pin (or hammer) crush them as fine as you can. If you use a wooden rolling pin, it can spoil the surface. Repeat will all the colours and keep aside.
Now cream together the butter and sugar in a large bowl, using a hand held electric mixer. Then add the date syrup/ molasses and vanilla and beat till mixed. Now add the egg and beat for a minute or so until smooth.
Sift the flour, salt and baking powder together and add to the bowl. Beat, on slow speed, until the flour is incorporated. Shape the dough into 2 equal disks, wrap well in cling film and refrigerate for at least 2 hours. This makes the dough easy to work with.
Working with one disk of dough at a time, place a disk between two large sheets of parchment and roll it out to between 1/4u201d to 1/8u201dthickness. This prevents using excess flour and also makes rolling out the dough easier.
Cut out shapes of choice with a cookie cutter about 1/2" apart, making sure you do not cut through the parchment. If you use parchment cut to the size required to line your baking sheets, then transferring the cut-out cookies to the baking sheets becomes easier. Cut out the centres of each cookie with a smaller cutter. You can use any shape you want but a round shape is easier to fill with crushed sweets/ candy.
You can bake the cut-outs as small cookies or all them to the scraps, re-roll and cut out more cookies from it.
Now transfer the parchment with the cut-out cookies to your baking tray. Using a teaspoon, sprinkle a little of the crushed sweets/ candy into the centre of each cookie (enough to fill the centre but not too much tor it will bubble out and look messy). You can mix colours in a single cookie for a mottled/ marbled effect.
If youu2019re planning to use the cookies as decoration on your tree, poke a small hole at the top of each cookie for stringing ribbon or cord through.
Bake the cookies at Bake at 180 C (350F) for 12 to 14 minutes till the candy melts and the cookies are firm to touch and a light golden brown. Let the cookies cool on the sheets for about 10 to 15 minutes before removing the cookies off the parchment or the centres will still be soft and separate.
Then cool them completely and store in an airtight container or use to decorate.