Don't panic Dutch - it happens to all of us. There are a number of solutions but either of these 2 work best for me
1. Use bicarbonate of soda and rub it off with a sponge or soft cloth or brush - don't use anything too wirey as it will scour the bottom but if you use the bicarb neat with just a dab of water and a lot of elbow grease, it should shift it.
2. Use half water and half vinegar, or even more vinegar, enough to cover the blades, and heat at 100, speed 2 for 5 minutes.
Hope one of these works for you.