Powdered erythritol is obtained by simply grinding erythritol in a coffee grinder or similar for a couple of seconds, in quick bursts; let the powder sit in the grinder for 5 minutes to avoid a cloud escaping as you remove the lid.
For the chocolate coating, the bowl should be fairly deep but not too wide as you will need enough depth to submerge the bites into the chocolate sauce (I used a Pyrex bowl 13cm diameter - 8 cm height).
Metric kitchen scales are an inexpensive yet invaluable gadget to enable accurate measurement of ingredients. Store them upright in a cupboard or over your worktop and they'll only take up a tiny bit of space. Click
HERE for the ones I use.