I am not familiar with lab blocks but I use
Science Selective food and soak some of the heart shaped pellets in some water to make a hammie porridge. I am using it with two of my girls at the moment and have used it in the past too.
Science Selective is available at most good pet stores and online. It's a great food and is versatile with being able to make it softer for poorly or older hamsters. It can also be crushed and added to dry mixes.
Same precautions go along if using Science Selective in this way....hamsters' teeth will not be worn away, so there will need to be harder food, chews etc available for their teeth. Check that teeth are not getting too long, as that will cause additional issues. If the teeth do get too long, then a vet can trim them.