In a large frypan on a med-high heat add butter and wait till melted. Add asparagus spears and depending on thickness sauté for around 5-10 minutes. Season with salt and pepper.
Whilst asparagus is sautéing toast bagels and prepare peas.
Spread 2 tablespoons of pesto onto each bagel half. Evenly spread 1/4 of a cup of smashed peas onto each bagel half.
Once asparagus is cooked place 4-6 asparagus spears on top of bagel. Sprinkle on crumbled feta and a good crack of pepper.