Close, but it’s the other way round, and it trips everyone. The names are from the Pi’s point of view: MOSI is the Pi sending to the chip, MISO is the chip sending to the Pi. DO on your breakout means “data out of the MAX31855”, so DO goes to MISO, GPIO 9, pin 21.
The MAX31855 never receives anything, you just pull CS low and clock out 32 bits, so it has no input pin at all. Leave MOSI (pin 19) unconnected. Wiring:
VIN -> 3.3 V (pin 1)
GND -> GND (pin 6)
DO -> GPIO 9 MISO (pin 21)
CLK -> GPIO 11 SCLK (pin 23)
CS -> GPIO 8 CE0 (pin 24)
Enable SPI in raspi-config, then read 4 bytes with spidev at 1 MHz or below. Bits 31..18 are the thermocouple temperature in 0.25 C steps, bit 16 is the fault flag. Check that flag before you send anything, an open thermocouple otherwise shows up as a strange number on your chart.