Hard Maple counter top finish

I have replaced a couple sinks and the hardware is usually included in the kit depending on what you order, under or drop in. With an under-mount you will be plagued by water damage in the exposed grain, my warning. Can't recommend a finish.

First I would recommend that a finish be applied to both top and bottom surfaces. 
The type of finish would depend on the anticipated use. The under mount sinks are problematic in that they expose end grain to high levels of water vapor. Those areas l would recommend coating with thinned by heat (not solvent) epoxy to help seal the grain. 
You’ll also need to decide what tone you want the top to have water white or something deeper. This needs to be applied prior to finishing. If oil stain is applied allow plenty of time for drying. Different shellacs will impart different hues. 
The shellac will also serve as a binder between the epoxy and the top coat as it sticks to everything and everything sticks to it. 
Considering its a counter top assume varying levels of abuse. The last thing you would want is a finish that cannot repair easily, precluding any oil modified urethane finishes as they have no “burn in” feature. This type finish is very difficult to repair. I recommend a waterborne finish such as Target(targetcoatings.com) as they are burn in and also have hardening additives available. The advantage here is that you’ll build a top coat that is one bonded surface so that any surface repair will not show the previous coat as a separate layer. 
I hope this “short” suggestion helps
If you need further help let me know
Ed

@Ed morini

I am already using the Target Coatings HSF5000 water based primer sealer for the cabinets before I paint them.  

So a clear shellac will be a better primer instead of the TC HSF?

Which clear top coat would suggest?  My wife wants more of a satin to semi gloss finish.

Thanks

The shellac will give you a slight amber tint to the maple. You could even dissolve dye stain (lockwood) to the shellac for more effect. 
This would be applied prior to the epoxy. 
That Target product is water white but can be tinted if desired. Good product but l have no experience using it with epoxy. The epoxy use here is really for water sealing(particularly around under mount sink), wood tone protection and toughness. 
I would recommend either the Target varnish or their urethanes for top coat as they are burn and brush friendly. Their reducer/extender would be helpful for brushing large areas. 
A satin sheen should serve well although any finish can be buffed to desired sheen. Matte would should the wood to its maximum effect. 
Also I’d call Jeff Weiss at taget for more info if needed