How do I convince wife/new SAHM to spend our money

Dad here - my wife is a new SAHM to our 15 mos old son, and pregnant with our second son. She’s a new SAHM since December and doing great. I would say when we were both working she handled the bulk of the child care, and I handled the bulk of the home tasks. I won’t lie, I am loving coming home to a cleaner house and not cooking dinner

But on to my question. My wife who worked her whole life before this, is as cheap as they come to start. I get the sense she feels guilty about spending our money now that she is not contributing an income. I don’t mean anything extravagant, but things like taking him out during the day to do things, or taking him to get lunch. She has a joint credit card and a joint bank account with no real restrictions other than common sense, but hardly ever touches it. What can I do to make sure she knows the money is there and hers?