Preheat the oven to 350℉/177℃ and line two large cookie sheets with parchment paper.
In a large bowl, whisk together the flour, milk powder, baking powder baking soda, and salt.
To the bowl of a stand mixer, add the butter and both sugars and cream together on medium speed (with the paddle attachment) for 3 minutes until the mixture has lightened in color and looks fluffy. Scrape down the sides halfway through and again at the end.
Add the egg, egg yolk and vanilla, then mix on medium speed for another 2 minutes. Scrape down the sides halfway through.
Add half of the flour mixture and mix on low speed until combined, then scrape down the sides.
Add the remaining flour and mix on medium low speed until combined.
Scrape down the sides once more, then add the freeze dried strawberries (break them up slightly before hand) and mix until they're evenly dispersed.
Using a 1.5 inch cookie scoop, level off each scoop and add nine dollops of dough onto a cookie sheet. This is about 35-40g for each dough ball.
Roll each piece of dough through the crushed cornflakes, then place them evenly on the baking sheet.
Bake the cookies for 8-10 minutes, then remove and give the pan a good smack on the counter. They will seem underdone and barely set on the sides - this is what you want.
Allow the cookies to cool on the baking sheet for about two minutes, then use a spatula to transfer them to a wire rack to finish cooling.