In a medium bowl, whisk together the gluten-free flour blend, salt, baking soda, and cinnamon. Set aside.
In a large mixing bowl, beat the softened butter and sweeteners together until light and slightly fluffy, 2–3 minutes, scraping down the bowl as needed.
Beat in the egg and vanilla until fully combined and glossy, about 1 minute. Mix in the orange zest.
Add the dry ingredients to the wet ingredients and mix on low just until no streaks of flour remain. The dough should be thick but not dry. If the dough seems crumbly after mixing, add dairy-free milk 1 teaspoon at a time until it comes together.
Fold in the dried cranberries and white chocolate chips until evenly distributed.
Cover the bowl and chill the dough for at least 45–60 minutes (or up to 24 hours) to hydrate the gluten-free flours and firm up the butter. This prevents spreading and gives better chew.
When ready to bake, preheat the oven to 350°F (175°C). Line 2 baking sheets with parchment paper or use a baking stone.
Scoop the chilled dough into 1½-tablespoon balls (about a heaping #40 scoop) and arrange them at least 2 inches apart on the prepared sheets. For thicker cookies, keep the dough in rough balls; for slightly thinner cookies, press gently to flatten the tops just a bit.
If possible, bake one sheet at a time on the center rack for 10–12 minutes, until the edges are set and lightly golden and the centers still look just slightly underbaked.
Remove from the oven and, while the cookies are still hot, use a large round cookie cutter or glass to gently “scoot” each cookie into a perfect circle if you like.
Let cool on the sheet for 5–10 minutes, then transfer to a wire rack to cool completely. They will firm up as they cool.
Store completely cooled cookies in an airtight container at room temperature for up to 4 days, or freeze for up to 2 months.