Preheat oven to 350°F. Line two large baking sheets with parchment papers or with a silicone baking mat. Set aside.: As the oven warms you will smell the faint electrical hum and the air will start to feel cozy, which is a nice cue that heat is building evenly. Lining sheets prevents sticking and promotes even bottom browning, giving a uniform golden edge around the cookies. A common mistake is not letting the oven fully reach temperature, which can cause uneven spreading and underdone centers. If your oven runs hot or cold, use an oven thermometer to check accuracy before baking.
In the bowl of a stand mixer, cream together butter and sugar until smooth and creamy.: When creaming you should see the mixture lighten in color and become fluffy, a visual sign that air has been incorporated to help with tender texture. The sound changes too, from heavy to lighter as the paddle moves through softened butter . Avoid overbeating, which can introduce too much air and change bake height; stop once the butter is pale and smooth. If your butter seems greasy, it was likely too soft and you should chill slightly before proceeding.
Beat in the molasses, canola oil, vanilla, baking soda, salt, and spices. Mix until well combined.: The bowl will darken and the aroma will shift to warm, spicy notes as the molasses and spices mingle. Combining the leavening with the wet ingredients helps it disperse evenly so the dough rises uniformly. Stir until no streaks remain, but do not overmix, which can make the dough tough. If you notice lumps of molasses , scrape the bowl and beat briefly to incorporate for even flavor distribution.
Add the eggs, one at a time, and beat until smooth. Slowly add in the flour. Next, stir in the white chocolate chunks.: Adding eggs one at a time creates a smooth emulsion and prevents separation. As you add flour , the mixture will thicken and become visibly doughy, a tactile change that signals readiness for chunks. When folding in the white chocolate chunks , use gentle strokes so they remain intact and distribute through the dough. A common error is vigorous stirring which can pulverize chunks and change the texture balance.
Scoop the dough into balls and roll in granulated sugar. Place on lined baking sheets, about two inches apart. Bake for 10 minutes, the cookies will still be soft. Remove from oven and let cookies cool on the baking sheet for five minutes. Transfer to a wire rack and cool completely.: The dough should feel cool and slightly tacky when scooped, and rolling in extra granulated sugar gives a sparkling surface that slightly crisps in the oven. Place balls spaced apart because they will spread gently; you should hear only a soft hiss from hot dough, not vigorous bubbling. Bake until the edges set and the centers still look soft, which keeps the interior tender as they finish on the sheet. A typical misstep is leaving them in the oven until fully firm which dries the centers. Allowing five minutes on the pan helps residual heat finish the bake without overcooking, then transferring to a wire rack ensures even cooling and prevents sogginess on the bottom.