You can try to strain through a sieve, but it's a total pain and might now work, depending how finely chopped the nuts are (whole nuts or large pieces should not be an issue). Maybe try a brownie recipe using unsweetened cocoa powder.
* might not work
sorry for the typo.
Don't! Just leave them in. You may want to use more chocolate to balance out the volume of nuts in the bar. Plus, more chocolate never hurt any brownie recipe I've made. :)
- melt and strain through a fine sieve (this will be a big pain and take a good while)
- leave in the nuts
- wait to make brownies until you have the chocolate you want to use