In a small bowl, whisk together the flour, baking soda, cinnamon, cardamom, ginger, and salt. Set aside.
In a medium size bowl with a handheld mixer, or the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and both sugars until smooth. Add the eggs and beat on high until combined. Scrape sides and bottom of bowl as needed. Add the vanilla and molasses and beat on high again until completely combined.
Pour the dry ingredients into the wet ingredients and beat well on low until combined. With the mixer still on low, add oats and white chocolate chips. Blend until everything is evenly dispersed.
Cover and chill the dough for at least 45 minutes or up to 2 days in the refrigerator. If chilling for longer than an hour, allow dough to sit at room temperature for at least 20 minutes before rolling and baking.
When you are ready to bake the cookies, preheat oven to 350ºF. Line 2 baking sheets with parchment paper or silicone baking mats and set aside.
Using a cookie scoop (I use this #50 cookie scoop for all of my standard size cookies), scoop dough into your hand and roll into a ball. Place on baking sheet at least 1 and ½" apart.
Bake cookies for 10-12 minutes or until edges just begin to brown. Remove from oven and allow to rest on baking sheet for at least 3 minutes. Cookies will look underdone, and will "set" as they cool on baking sheets. Cookies stay fresh covered at room temperature up to 1 week. Baked cookies freeze well, as does unbaked rolled dough (up to 2 months). Do not thaw and add an extra minute to baking time.