Place puff pastry cups on a baking sheet and bake for approximately 15-18 minutes or until they turn golden brown.
While baking, saute chopped ham in a skillet with 1 tablespoon butter until golden brown.
Whisk eggs and 2 tbsp. milk together. Whisk in the chives and cheese. Add 2 more tbsp. butter to the same skillet and add egg mixture to ham. On low, scrape bottom of pan with a wooden spoon until fully cooked. Low and slow is key to soft, fluffy eggs! Remove from pan when done.
Add flour and butter to a small saucepan and whisk on medium heat until bubbly (about 1 minute).
Add milk and whisk until thick, about 5 minutes. Add salt and mix in before taking off heat.
Take your pastry cups and spoon a little bit of egg filling into the center of each.
Top with sauce and chives and serve warm!
*These can be assembled and kept warm in the oven until guests arrive! You can serve with the sauce on the side although who wouldn't want it over top?