Cut each squash in half; remove seeds. Place squash halves, cut-side up, in Multipurpose Steamer. Season with aioli mix. Cover; microwave on high, 10 min or until tender.
Meanwhile, melt butter in a fry pan over medium-high heat. Add chicken and stir-fry until cooked through, 8–10 min.
Add coconut milk, tomatoes, and seasoning. Bring to a boil. Reduce heat to low and simmer 5 min.
Divide half the chicken filling evenly among each squash boat. Reserve remainder for later use (freeze up to 1 month). Top each boat with cucumber, if desired.