Modern granny stitches are beautiful, but with thicker yarns like Bernat Blanket, the chain-3 gaps can be excessively large. I wondered about the possibility of locking the rounds together and used a double crochet spike stitch to close the gaps while keeping what is lovely about the concept. This is the crochet locked modern granny stitch blanket
 
The pops of colour from the single crochet in the chain-3 rounds expose different stitch colours, making it very desirable. 
 
The colours come out in the ball as shown, and let them land where they may. If you prefer this concept with a colour strategy, go for it. 
 
Bernat Blanket Patchwork, 300 g/10.5 oz, 201 meters/220 yards
 
A - Citrus Stack - 4 Balls
 
Hook: 8 mm / L/11
 
Match the hook to the yarn ball band recommendation if substituting.
 
Gauge: 10 sc and 8 rows = 4” [10 cm]
 
Blanket Size: 46” x 46”
 
You will need more yarn if you want to make it bigger.