Slice the peaches and lay single layer on a cookie sheet covered with parchment or plastic wrap.
Place the raspberries separate from the peaches on the same cookie sheet. Freeze 3 hours or overnight.
Remove from freezer and let sit for 10 minutes.
Using a small amount of the peaches at a time (maybe 6 or 7 slices) drop them in a food processor fitted with a sharp blade and process. You will need to stop it occasionally and scrape it down, be patient, until it reaches sorbet consistency.
For each batch add a bit of sugar to taste (I usually use about 1 tbsp, depends on how ripe the peaches are).
As you finish each batch, place it into a bowl and put in the freezer (mix each batch into the subsequent batch.).
When you are done processing the peaches, pour all the raspberries into the processor and 2 tbsp sugar, process as above.
Dump the raspberries on top of the peach sorbet and fold in with a spatula.
Drizzle with a little chambord or limoncello if desired.