Hi Maria,
With a Base ticket, you are only permitted to enter one theme park per day. With a Park Hopper, you can visit as many parks as you'd like. You will need a ticket to enter any park, even if you are just there to dine in a restaurant. In order to eat at the
Hollywood & Vine and spend the rest of the day at the Magic Kingdom, you'll need to purchase a Park Hopper pass. Since you're only there one day and only want to visit the one park, I'd find somewhere else to eat. The price difference between a Base Ticket and Park Hopper is significant.
I recommend that you book Chef Mickey's, 'Ohana or the 1900 Park Fare instead for breakfast. These are all located outside of the parks, inside the Disney Resorts (so no ticket is needed). At Chef Mickey's you'll find Mickey, Minnie, Goofy, Donald and Pluto. At 1900 Park Fare you'll join Alice in Wonderland, the Mad Hatter and other Wonderland friends
for the festivities at the Supercalifragilistic Breakfast. At 'Ohana you can dine with Lilo, Stitch and friends.
Have a wonderful vacation,
Kaylene