Combine pineapple juice, milk, 6 Tbsp melted butter, and honey in a microwave safe bowl and microwave until mixture registers 110°F, about 1 minute (Mixture may appear curdled which is okay). Fix mixer with dough hook and generously spray hook with cooking spray. Mix flour, yeast, and salt on low speed until combined, about 5 seconds. Slowly add pineapple juice mixture, followed by brown sugar, egg, vinegar, and vanilla and knead on low until dough starts to pull away from the bowl, about 2 minutes. Increase speed to medium-low and knead until for approximately 5-7 minutes or until dough is smooth and elastic. (Dough should clear sides of bowl but will stick to bottom.)

Remove dough and spray mixing bowl with cooking spray. Knead dough into a ball and place back into your greased mixing bowl. Cover tightly with greased plastic wrap and let rise at room temperature until doubled in size, about 1 1/2 -2 hours. Spray a 9x13 pan with cooking spray. Set aside. After dough has doubled, remove to a floured surface (or mat) and punch down then lightly shape into rectangle of uniform thickness. Cut into 18 roughly even pieces then shape into balls by folding the corners under so that the top is smooth.

Arrange dough balls into 6 rows of 3 in prepared 9x13 dish and cover loosely with greased plastic. Let rise at room temperature until doubled in size, 1 to 1 1/2 hours. Adjust oven rack to lower-middle position and heat oven to 375°F. Remove plastic and brush rolls with approximately 1 1/2 Tbsp butter. Bake until golden brown, about 20 - 23 minutes, rotating dish halfway through baking. Let rolls cool in dish on wire rack for 10 minutes then brush with remaining butter. Best served warm.

To reheat rolls, wrap in aluminum foil, place on baking sheet, and bake in 350-degree oven for 20 minutes.