Mom's Caramel Corn

One of my favorite things to do on vacation with my family growing up was to sit and watch movies.  We'd eat popcorn, tortilla chips, and nacho cheese.  On special occasions my mom would make her caramel corn.  I'm not sure where she got the recipe but I know it because she made it for us.  Tonight I attempted to make it.  I did not have any butter, but I used some healthy butter stuff I had, and I read the ingredients wrong, I added cornstarch in addition to the marshmallows.  But I found the correct recipe and it said OR corn syrup.  Anyway, so I messed up all together.  The kids and Aron gobbled it up, it still was good, but of course, not mom's.  Man, I wish she was here so I can ask her how she really made it.  I'm pretty sure this is correct below, I'll add photos when I make it correctly.

Update: success!  I did it correctly and will provide the correct directions and ingredients below.

Ingredients: 

1 1/2 cups of mini marshmallows (what I did) OR 7 large marshmallows OR 2 T. corn syrup

1 stick margarine

½ c brown sugar

¼ t. baking soda

Directions: 

Combine first 3 ingredients.  Cook 3 minutes at 50% power.  Add baking soda and stir.  Cook 30 seconds at high power, or until marshmallows are melted.  Pour over 3-4 quarts popped corn. I believe I actually did 4 quarts with two batches of the sauce cause who doesn't love too much caramel?!