Recharging Time: 4.5 hours (with 18W USB PD charger & USB-C to C cable)
USB-C Input (PD): DC 5V=3A, 9V=2A, 15V=1.2A
USB-C Output (PD): DC 5V=3A, 9V=2A, 15V=1.2A
USB Output : DC 5V=2.4A
Total Power Output: 18W
The minimum cost charger which does this is the Nano, you are in Denmark so you need the Euro socket type.
Any charger which is Power Delivery and at least 18W will suffice to recharge the Powercore as fast as possible, there is no harm in getting more powerful if you have other needs also using Power Delivery. Power Delivery is a specific protocol.