My first doughnut in six years.
Morrisons sell a frozen pack of gluten free mini ring doughnuts. Defrost before eating, 10 seconds in the microwave. THEN using a kids plastic medicine syringe (comes with Calpol etc) suck up a syringe full of jam and gently inject one syringe worth into the inner ring of the doughnut. I managed to spread it out over three squishes.
Result, one warm jam doughnut.
You're welcome 
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