First time making a berry galette. The filling seemed too runny/soupy. I assume this can be remedied with adding more cornstarch. I used a sheet of puff pastry and baked at 425 degrees for 25 minutes per the recipe. The bottom was kind of rubbery and hard to cut with a fork. A different recipe called for baking longer at 375 degrees. Would this help or is the filling too soggy? I have read about using a layer of cornmeal or almond flour under the fruit. Does cooking the fruit is a pan for a short time with the sugar, flour and cornstarch help thicken it?