Hi, Tyler,

Since this forum is for Home Decorating, there probably aren't many woodworking experts here. You may have better luck getting an answer in the woodworking forum - http://ths.gardenweb.com/forums/wood

Or, Google brackets to support 90lbs, and you'll come up with some options, such as at this link - https://www.countertopbracket.com/

"Countertops made from granite, marble, quartz, Silestone, Corian and
even heavy butcher block are becoming very popular. Kitchen designers
and homeowners are pushing the structural limits of these solid surface
materials as they become aware of new trends and materials available to
them. Accordingly Centerline Brackets specializes in manufacturing high
quality countertop supports designed to safely support and bracket
commercial and residential applications.
"

Hi Tyler, this website should have all the brackets you need.

https://originalgranitebracket.com/

Also if you're using the butcher Block as a bar counter you may want to use an epoxy resin finish as it really makes the wood pop. Here is a table that we just finished.

http://www.etsy.com/shop/RedDogsCrafts

You could also try the LumberJocks Woodworking forum. I've gotten good advice here.