My Husband is never home during "dinner" prep either.
He is at work. That doesn't matter if he is home or not.
Your 6 year old must be in school.
The 3 year old, is he/she in Preschool?
If so, with both of them being in school (and only 1 at home then)... THEN, when they are at school, THAT is when, you prep dinner/meals.
Me: my kids are now 6 and 10. BUT, ever since they were born, I prepped dinner when they were napping. Or, when they were in Preschool.
Now, with both my kids in school, THAT is when, I prep dinner.
And yes, even if that is in the morning. By the time I pick up my kids from school, dinner is already prepped, or already made... and then all I have to do is cook it or heat it up. Homemade, made from scratch, meals.
Just make use of your timing... to things.
Time management.
Dinner does not have to be made, AT dinner. It can be made, at any time PRIOR, to the actual dinner. ie: when the kids are not there.
Then, when your kids are there... kids typically get cranky/naughty... because they are either: tired or overtired, or hungry.
Do your kids nap?
But my kids, even in the late afternoon or early evening, even when they were younger, they didn't make much trouble at that time even if I was in the kitchen, busy.
OR, get a Superyard play pen, and put your 19 month old in that, while you are in the kitchen. Or put him in a room with a baby gate on it.
Then tell, your other older 2 kids... do not go by baby. ie: when my youngest (my son) was so active when he was a baby... I simply told my eldest child, "don't go by him.... or there will be trouble." And my eldest understood completely. Because, ALL kids, do not have to be in each other's hair... they can, play by themselves or somewhere else. Not being IN the other kid's personal space. And I know my kids moods... and sometimes they just get more fussy, when the other kid is in their face. So as siblings... my kids have learned each others cues. And they know when to stay away, from the other, if the other is grumpy or whatever. And that solves a lot of trouble.
I taught my kids, to know the vibes/cues of their sibling.