McDonald was 5-under the card after eight holes in her first-round clash with former HBPB rep Kathy Olsen, 4-up at the turn and went on to win 5 and 3.
It put her into a semifinal against HBPB teammate and provincial stalwart Janie Field (Napier).
The pair know each other's game well through the rep scene but McDonald said it was the first time they had met in a match.
McDonald eased to a 4 and 3 win to seal a place in the final.
Determined to go one better than her 2020 loss in the final to Palmerston North's Lily Griffin, McDonald played par golf against Choi and it was good enough for another win on the 15th.
“It wasn't spectacular, just consistent,” she said.
“I was really pleased with how I played over the weekend. I was really consistent.
“My putting was particularly good. It saved me a lot.”
McDonald capped her victory by winning a special shootout held on the 18th hole after the final.
Several players qualified for the final, which was decided by closest shot to the pin. McDonald almost holed a 52-degree wedge shot to win it.
Poverty Bay member McDonald is going all out this year to see if she can develop her game to the point of going professional.
She will be playing in several major events, including the New Zealand strokeplay at Paraparaumu Beach in March.