If you're working with frozen blackberries, allow them to thaw.
Measure out 3/4 cup of sugar and add it to your saucepan.
Measure out one cup of water and add it to your saucepan, pouring it directly in with the sugar.
Measure out one cup of blackberries and add them to your saucepan, pouring them directly in with your sugar and water.
Place your saucepan of sugar, water, and blackberries on your stove over medium-high heat.
Bring your ingredients to a simmer, stirring occasionally. Your berries will start to change color from their standard dark purple color to very dark pink.
Heat for 10 minutes until your sugar has dissolved. 10 minutes is all it takes for your blackberries to soften. After 10 minutes, turn off the heat.
Remove your pan from the stove and place it far away from the heat. While your simple syrup is still hot, smash your blackberries.
(While you can use a proper tool like a potato masher, a handy-dandy fork will do just fine.)
Smash until the simple syrup is dark purple and there are no distinguishable berries.
Cool for 10 minutes.
Once your simple syrup is cool, carefully pour your syrup through a strainer, either into a liquid measuring cup or directly into your mason jar.
After the syrup has passed through the strainer, all you'll have left is blackberry pulp. Using the same spoon, you stirred the pot with, use the bottom side to press as much liquid as possible through the strainer.
Note: There's a lot of hidden flavor in the berry pulp, so don't be afraid to really mash your spoon against your strainer (without breaking it, of course).
If you used a liquid measuring cup, pour your simple syrup into your mason jar. Enjoy for up to 4 weeks!
Pro tip: If you've tuned into my How to Make The Easiest Simple Syrup for Cocktails guide, you already know how tedious the cleanup process can be if you've allowed your crystallized sugar to harden in your pan.
Once you transfer your simple syrup into your mason jar, clean your pan. It'll save you so much headache later, I promise.