That seems like the inverse of sugar-to-butter than most cookie recipes I've seen and used. Usually, the basic rule of thumb for cookies is a ratio of 3 flour : 2 butter : 1 sugar by weight (give or take depending upon other ingredients, etc.) Would you consider trying your recipe, except using 1 cup of sugar and 2 sticks (1 cup) of butter with the rest the same? I think you may see a big difference in texture.
[If you notice, your recipe's ratios are somewhat different than the basic 3:2:1--even with the change--because you have an egg and egg yolks in it, which provide extra fat and liquid. That's why you can afford to use more flour than the basic ratio and essentially less butter/fat.]