Beat butter and sugar together on medium speed with paddle attachment until light and fluffy (mixture will appear pale yellow).
Add egg and mix on low and stop once egg is incorporated.
Mix dry ingredients together in separate mixing bowl and whisk until combined.
Turn mixer on low, add 1/3 of dry ingredients into wet ingredients and mix for 5-7 rotations then stop.
Add another 1/3 of dry ingredients, mix on low for 5-7 rotations then stop. Use spatula to scoop side of bowl and mix for 3-5 rotations.
Add final 1/3 of dry ingredients and repeat this process. Don’t worry if there is still some visible dry ingredient as you will incorporate white chocolate in next step.
Add white chocolate chips and mix on low for a few rotations until incorporated.
Place dough mixture on cling wrap and roughly shape into a ball.
Roll dough back and forth between your hands until a log forms. Start shaping log into a rectangle by patting and smoothing with your hands.
Wrap rectangular dough in cling wrap and allow dough to firm up in the fridge for 30 minutes - 1 hour*.